things might be hard right now, but they won't always be hard. And look at it this way, things don't go wrong to make you bitter, they go wrong to break you down and build you up in order to make you the one you are supposed to be, because only through trials of suffering can humans achieve what they really want. Learn from your past, always, but don't live it again. What you went through in your past is your experience, maybe it was bad, but you also learned a lot, and that is never wrong. And yes you are human, you are supposed to make flaws, everybody does. You can't possibly know the right thing from the beginning. And you know something else, I have regretted things I didn't do much more than things I did. Even if they were bad. I was introverted like you back then, and so what? it was me back then, another version, my character has changed since then, a lot. Don't focus on your past, focus on your future, and a lot on your present, as they say "yesterday is history, tomorrow is a mystery, but today is a gift". Plan for the future, but also live each day as if it was the last one.
Stop dweling with what you do not like, start doing things to make your goals happen, remember there are doors that close and others that open, the difference is what you do stare at the closed doors or rush to the new open ones.
I'm in graduate school too, with 2 and 2/3 more years to go before I'm done and have opportunity to get a good, well-paying job. I don't have any friends. Honestly, friends are easier to maintain with free time and money, which is what both of us will have when we graduate. Hang in there. Appreciate the friends you do have. Spend the time you're using feeling sorry for yourself either studying or working on your art. As for your family's financial problems, you'll be able to pay them back in two years. They're counting on that too. So hang in there. It WILL get better. You just have to get through school. Focus on becoming an excellent (or at least competent) lawyer, and everything else will fall into place.
Well not everyone that graduates from law school becomes a lawyer, knowing the law helps you in a wide variety of things. So think it like this: now your family spends a lot of money on you but after you graduate, even if you don't do the exact job that you studied for, you will be able to pay them back. And if you don't want to pay them back rightaway, think it like they are investing on a good pension. When they get old you can take care of them.
Even if you think that law is not the thing for you, don't forget that you can always study a second or third time later. You still have time.
Even if you are failing at your classes, you can always ask for help from or befriend your instructors. They usually like directing students. Besides if your peers are not very good friends, maybe your teachers are.
And yeah if you are not shy than just take a shot and befriend someone. A good time always helps and loneliness is actually the base of all human problem.