3 years old is a hard age.
You need to know about age-related development.
Get books, or look it up online.
Then, 16 months old is a different age development.
3 years old and 16 months old, is vastly different.
Older siblings, often are "expected" to be the "example" for their younger siblings. But this is not fair. Because, they are little kids themselves who don't have complete knowledge about life or how to be a sibling. So you need to teach this to the children. Eldest siblings, often get "stress" too. Because of all the "expectations" upon them. But they don't know how to ... handle it all. They are still developing too. And are young. They don't have fully developed "emotions" yet nor brains. Nor impulse-control. Nor do they even have the vocabulary to say things, they don't even have the ability to articulate and express themselves in a perfect way. It is taught. They don't even know the "names" for their feelings, nor how to express it. It is taught. Nor do they have, fully developed "coping-skills" nor deductive or inductive reasoning skills. It is taught.
And kids at 3 years old and older, do get "bored." And they have different needs, than a baby. They need.... more socialization, more physical activity, more interaction. This is a good age for Preschool.
Kids this age also need structure. And they respond well to "routines." A child needs to know... what is coming up next. And you can also begin to teach her things. ie: her alphabets, colors, shapes, numbers, etc.
Staying home with a child or children, takes a lot of effort. And yes, it is not easy.
You can also teach the oldest, about how to "help" you. And then "praise" her verbally, for it. A child this age cannot clean the house just like an adult. But, you can teach her to "try your best...." and teach her how to wipe the tables for example. How to "help" you. But not in a way that pressures her. Some kids, will resist... because they think they have to do things... PERFECTLY, so that they don't get scolded. So then they don't want to do it at all. But it is only because, of the "expectations" that are upon them.
Kids this age, who are toddlers or 3 or 4 years old, don't know how to handle all of life's difficulties or frustrations. Not even some adults know that. So keep "expectations" age, appropriate. Teach her, that she can communicate with you. Talk with her. Let her express herself to you. Teach her that. It is also "bonding" with the child.
Kids this age are not perfect. Nor can they be perfect. And they will make "mistakes" over and over again. It is childhood.
But as you teach the child rules.... they will learn. You also need to role-play with her. Teaching her how.... she can say things, in a more palatable way. This is the age that a child needs to learn this.
It is taught.
It is not a skill, that a child has automatically.
Many kids, also need to know why... not just told "no."
Explain things to her.
But just encourage her to "try your best...." So that, the child can... attain, a sense of mastery over their reactions and problem-solving.
Kids don't automatically KNOW how to "problem solve" for their frustrations. It is taught.
The "Eldest" child.... is often expected to do and be, so many things. Of which, they are not even developmentally able yet, to do or be.
Hence, they get frustrated.
When I had my 2nd child.... I was very careful about my eldest and spending tons of time with her. She needed more "bonding" with me, since her brother was born. My daughter was about 3.75 years old at the time. But although I was careful with her and talked with her often... she once told me "Mommy, I'm just a little girl, not an adult!" and right there, I realized all the "stress" she had... in her little child's mind... about her place in the family. And about how... things were affecting her.
The Eldest child, has a lot on their little shoulders.
And they need for us to realize that.
My daughter due to her age, had different needs. And at that age, she went to Preschool and loved it.
And I had to spend a TON of time, on her, per her age and development.... because at this age, they need Mommy more. Not just time-outs and scoldings and being told "no" all day. They need interaction and quality time. And to feel important, in relation to their younger sibling.
Kids this age get frustrated.
And they need to be taught... about how to handle it all.
I have been a SAHM for about 9 years. Since my eldest was born.
Sometimes, and eldest child will act like that, frustrated, because they need us more, at that time.
You have to be able to "discern"... when your child is being willful or just needing you more. And talk with her about "why" she is frustrated. It will take practice. They need us to "hear" them, as much as we want them to hear us.
That is how... you build a "relationship" with your child.
And this is very important. And it will teach your child that they can, communicate with you.
Once, my son got scolded by my Husband. Why? Well, my son was cleaning the room/wiping the tables while my Husband was exercising. And my son dropped something by accident. Well, to my Husband all he thought was that my son was being "noisy." And he scolded my son. Well then my son started crying. And then my Husband scolded him for that "noise." But my son did NOT do anything "wrong." He was cleaning. And was proud of it. So then, my son told my Husband "I am upset that you scolded me... I didn't do anything wrong! Go away!" It took my Husband a few seconds, to realize that he was not being, cognizant of the situation because he scolded my son for HIS frustration... and my son was not doing anything "wrong." My Husband was just irked, because my son dropped something by accident. It was not something "wrong" my son did. He was being a kid... and was helping cleaning.
So, my Husband APOLOGIZED.
A parent, has to realize these things to, and to be able to discern the child and the situation. And to also, recognize that.
It is not with every little thing, that is wrong.
You need to teach a child... about things.
Adults are fussy too.
Adults are crabs too.
Adults vent too and don't know how.
Adults have bad days too.
But adults are supposed to know how to handle it. Some don't.
So for a child of 3 or 4 or 5 or 6 years old, they are needing to be taught, about how to manage... this too.