Not sure if this is depression, or something else...

Some background information first I guess- I'm 21, in my second year of university. My first year of univeristy was incredibly bad. I struggled to befriend people, and the one person in my course whom I did get along with died a few months after I met her. I was of course extremely distraught, and from then on making friends was impossible as people in my course were too awkward and uncomfortable around me. The one thing that kept me going was my course itself. It turned out to be such an interesting subject and for the first time I knew what career path I was interested in going down. I studied often and diligently, and my grades were excellent despite my general unhappiness and lack of a social life.

Then year two started. I joined the university debating club, and just like my course it unexpectedly turned out to be something I am good at that I loved doing, but more importantly I quickly made some amazing friendships. I also got offered 2 amazing paid internships at pretty excellent law firms over the summer. My social life, sex life, and career prospects have never been this great.

But for the past 12 weeks, I have had zero focus or motivation or energy. I can't get out of bed, sometimes I just lie there until I get too hungry to stay curled up. Worse, I can't study. Now, I know all about procrastination - I've always had to force myself to start homework or study, but once I got started and started accomplishing even something small, that feeling would grow until I was in a pretty good productive mood and I could work for hours. At times when it got especially hard to study, I always had a number of tricks to motivate me - listening to music, or just looking at career ads in my chosen field (maybe I'm materialistic, but the thought of earning six figures before I turned 30 always filled me with a huge amount of determination to get studying) and sometimes just looking at silly inspirational videos on the Internet.

I've dealt with depression before. I've had a remarkably shitty childhood and family life and I'm currently trying to care for a parent that's been suicidal for at least as long as I've been alive and is deteriorating. I've always been able to handle it somewhat, especially after discovering how much exercise helps with that. I felt depressed a lot last year given how badly university was going, but what's happening to me now just doesn't feel the same. I'm not sad or overly stressed out, just completely... lethargic. Unmotivated, despite the tricks that have always worked before. I can't get started studying, and when I do I don't get the same feelings of interest or satisfaction so I can't focus or keep working for more than a few minutes. I'm not even watching TV or playing video games like I normally would while not studying, I'm just kinda doing...nothing. I can't even get the energy or the enthusiasm to enjoy games or reading or food, let alone textbooks (though I always loved studying, and I should really love it even more now that I've got a general idea of what direction I want to take my career in). I don't understand why I'm like this and nothing I do is helping.

Is this depression, just different to what I experienced before? Someone also suggested anaemia, so I'm going to go to a doctor for a blood test on Monday to get checked out. Hopefully he or she will help me with all of this, but I just wanted to ask for reddit's opinion in the meantime. I'm slightly worried about the idea of being prescribed antidepressants within a few weeks of exams and starting my internships, but I'm more worried about failing out of college because I can't beat this. Especially when I don't understand why this is happening now.

Thanks for reading, any advice or anything is welcome.