L.,
I think it may be time to be kind to yourself. To take care of yourself. All the people who say, "cheer up!" can go fly a kite.
Okay, let's name the amazingly difficult things you are handling right now;
1. Going to school
2. Living with the in-laws
3. Raising a toddler pretty much on your own
4. Creating life in your own body
Sheesh, woman! You've gotta go take a nap! Any one of those things is enough stress on it's own. And you have to do each and every one of them every day? No wonder you feel defeated, deflated and depressed! You are basically superwoman, did you know that?
I think you should talk to your OB/GYN about your feelings and worries immediately. Today. I guarantee just picking up the phone and getting the ball rolling will eleviate some stress. Also, I liked the suggestion some one made about talking to an on-campus counselor. Treat this just like any other medical symptoms you are having, because I guarantee that this is medical. Pregnancy hormones get the blame for a lot of things - and rightly so. They can wring you out, twist you up, make you into a crazy woman. I went through it with my second as well and I am pretty familliar with what you're feeling right now.
Aside from talking to your doctor, please take the time to be good to yourself. I know you don't have time right now, but try and indulge a little 'you' time when you can. Be greedy. You need to.
All the best to you