I am 20 years old, passionate about social change & having trouble in university; what can I do with my life?

I'm nearly 20. I lived on campus at two different colleges and withdrew from both because in both cases I became very, very depressed. After taking nearly a year off to focus on reflection and therapy for my depression, I went to a regional campus of a state university. And although I went full time and took pre med classes, (Yes, my classes were comparable to a large university, because we would get essay and extended math questions, while the large campus students always had multiple choice.) I nailed a 4.0, which, is pretty awesome for having ridiculously hard professors in lab. Anyone who's had lab realizes that you get 12 credit hour for lab, but the class is at least 3-4 hours, and you spend around 12 hours + a week outside of school doing work just for the lab. Anyway, I digress. What I am trying to say is that I can get through college. Sadly, I became super depressed this semester. I took the necessary steps to gain my composure to at least pass the semester with C's. I continued seeing a therapist and psychiatrist and over my spring break, I volunteered in a big city so that I could experience something beyond myself. Unfortunately, I continued to crash. Now it is finals week, I'm working on a withdrawal or incompletes for medical reasons, and I can hardly make it out of the house. My town and university do not help my depression. I am passionate about volunteering and social issues, and doing that is what makes me happy, but I still need an education. I was that perfect student in high school who always went above and beyond because I wanted to make a positive impact in the world. Right now, I'm focusing on the small things, like making it through a semester of college, but clearly college isn't working well for me right now. I tried working a minimum wage job a few years ago, but I would get in trouble with the manager a lot for not doing well. I worked my butt off, yet I had major anxiety, so I would "mess-up" a lot. I thought about the Peace Corps, but I am not psychologically and physically healthy enough for that right now, and it would be best if I got a bachelor's degree first. I'd love to travel across the world, living out of a backpack, but my family lives pay check to pay check and I have student loans. If I leave college full time, I will lose my health insurance, which I use a lot, and I will have to start paying on my loans. I'm in the middle of a very serious existential crisis. (I hope to start volunteering over the summer to help with that.) I know that this question rambles on very horribly, but I am truly at a loss of what to do. I've tried sucking it up and finishing college, but I become further depressed. I want to experience the world and help people, which is hard to do without a degree. I suck at minimum wage jobs, which are not enough to support myself and pay back my student loans, and they do not give health insurance. Any feedback? **Yes, I will personally choose a best answer.**