I added more thoughts the next day after writing this. Your plight hits me in a sensitive spot. I know you can change it!
Have you reminded her, each wèek, to pay you? It should not be demeaning to ask for what she already agreed to pay you. She should be embarrassed for making you ask. Frankly, your post sounds like you're in victim mode. Sounds like you don't feel appreciated. How is your relationship with your daughter? Perhaps, along with asking for pay, you praise her and her husband. I'm guessing they're reacting to your attitude. Now you and your daughter are stuck in this not helpful way of relating.
I suggest that improving your relationship with your daughter will improve the way you feel. First ask yourself, do you really want to be this involved for this many hours or are you doing it because you feel obligated? The way you feel about watching your grandchild greatly affects the way you feel about the situation.
I also suggest that your son-in-law has responsibilty to make this work for you. He needs to stay home so you can go home earlier. It's reasonable for you to expect that.
I know this from experience. I was the full time caretaker for my first and second grandchildren. My daughter really couldn't afford to pay me. I enjoyed watching the babies and felt unappreciated by my daughter. We also had difficulty talking with each other. Both of us felt judged by the other. We worked first on our relationship. Once we felt better about our relationship, we began to be able to talk about what each of us needed.
So, remind her each week in a friendly way. Do you know for sure they can afford to pay you? What is there income and expenses. Do not ask them. Observe and intellectually figure it out. Consider that they may not be able.
If you don't want to give them this much time, tell your daughter in a diplomatic way. You do not have to help them with childcare! They chose to have this baby. They, not you, are responsible for her care. If you don't want to reduce hours or if you want to care for baby and they can't afford to pay you, consider other ways that will make this better for you. I liked babysitting better when she brought baby to me. I had duplicate equipment at my house. I also liked it better when I was able to take my granddaughter with me to run errands, do things for myself. Consider changing conditions for your care.
I urge you to consider and make better boundaries for yourself. You cannot change your daughter but you can tell her what works for you. You do have the right to get paid. If they don't pay you, you also have the right to say you can't do this full time or not at all. Or, as I do now, help out and/or spend time just as Grandma. When you talk with your daughter be confident in those rights. No blaming. Just, 'I can't do this anymore. How they respond and how they get childcare is up to them. You do not have to feel guilty. You do not have to be the only caretaker. You are doing them a favor. They need to recognize that and treat you accordingly. At the same time, it's your responsibility to respect them and their decisions for their baby. No judging. "I'm able to do this for you and to do this, I need this from you. "Good fences do make good neighbors." Fences are boundaries."
Both my daughter and I had difficulty separating my roles as caretaker and as Grandma. Once I became only Grandma, I could enjoy the time I spent with them. I became a babysitter but only when I wanted to be.
My daughter and I needed a couple of years to work this out. First, we had to respect each other. I had to stop giving advice. She had to accept my doing some things my way. We had to become equals in decision making. Most importantly, we had to stop judging each other.
You decide what you need and accept her needs. Then spend time talking with each other over a period of time.
BTW: for a year or more the state paid me to be care taker. My daughter was single and going to school. That may be a possibility for you, tho it sounds like they wouldn't be eligble.
Why do you think asking or reminding them to pay you is demeaning? If you were working for anyone else would you feel asking would be demeaning. Your daughter said they'd pay you. You're just reminding her of her agreement. You do deserve to be paid.
I believe they are taking advantage of your willingness to go over anytime for any length of time. They take advantage because you let them. Tell them you'll babysit only while they're working or for a certain amount of hours. That is fair!!! Actually, more than fair! They are so fortunate you're able and willing to help them. And......you deserve a life of your own. Perhaps you wouldn't question your right to be paid, your right to be rested and have your own life, if you respected yourself. You have to take care of yourself first before helping anyone else. You'll be a better grandma to your grandchild when you work less hours and have 2 days off like everyone in the work world. You need that time off.
Business has learned that their employees are more productive when they work 40 hours with 2 days off. Your daughter and her husband have 2 days off. They do not need you those two days. They need to spend that time with their child. Sounds like you are the mom. They spend very little time eith her.
They want you so they can do and buy things for themselves. Children, even adult children, need limits and be allowed to take on their responsibilities. They chose to have this baby. You are a grandma; not a servant! Most young families do not expect Grandma to do full time child care. Very few Grandma's help much and even fewer help as much as you do. I'm angry for you! Please step back and take care of yourself. You earned time for adult activities, to be child free. Did you have someone devoting full time to care for your child/children? Perhaps you didn't have to hold a job. Today is different. Most mom's have to work. They still have full responsibilty to provide care for their children. When you do everything for them they don't have to be responsible parents. They are acting as the young adults they were before they became parents.
You're not responsible for anything, except to be a grandma. You have become a door mat. I understand why you feel a victim. However, people become victims because they allow themselves to be victimized. Take control of your life so that you're not victimized.
My daughter resented me and felt I'd taken over her life. With professional counseling she learned that she has control of how much I'm in her life. When she found ways to make things happen, herself, our relationship improved.
Another thought. My daughter doesn't need help in the morning even of it would be helpful. She has 3 children under 5. The youngest is 6 wks. She is on maternity leave. She had a 2 yo and 4 yo and was able to get ready for work with only the help her husband gave her. It did take time for her to get a routine and be able to do it in less time. She is proud of herself. I'm proud of her too. I suggest you're preventing your daughter becoming a responsible adult.