I'm at a loss as to whether my feelings are valid

I feel bad all the time. I constantly feel low and like nothing matters. What will happen is that for a series of days (say, 3 or 4) I'll feel especially bad, and then for another series of days it will be much more managable, though the change is minor. This has been going on for 3-4 months. I think it started when my boyfriend had to leave for a program since he's a cello prodigy. I live about 1k miles away and we still keep our relationship going since we don't plan on breaking up any time soon. Distance matters little. I think I'm feeling so lonely because of that (regardless of how we call or text, though it helps immensly to call) and because my only friend is now duel enrolled and we never really get the time to hang out. We did recently, though, but then when she asked if I wanted to go to the fair in the next month I said no because I'm swamped and preparing for so much. I think I pissed her off... So the two people I care about most are pretty much at a distance. My parents are jerks and that would need a seperate post because they're just so petty and narrowminded and ridiculous. Basically the only time I can get where I'm not in a bad state is when I'm practicing my violin. But then I worry so much about my future regarding it, since it's going to be my major of study. I break down because of it. I cry at least a few times a week, I find I've become a big crybaby recently. I work my butt off, too. School for one half of the day, then practice for about five hours, then homework till around 1 or 2am. Sometimes I have days where I crash and burn-- not surprised. At my violin lessons i get really anxious and I freak out because 1) I'm going to sound like crap, 2) my teacher will be disappointed, 3) I'll be disappointed, 4) my future is f*cked, 5) I'll go nuts in front of her. Two days ago I had another lesson where I broke down. I've only done that once in front of her but this time I managed to keep it before it ended and then I did it, but not in front of her. While playihng for her I started and bc/ I didn't warm up (there's no time..) I sound bad and I start feeling crazy and hot and troubled so I ask her to start on Bach instead since that's how I always do it, Bach and then my other piece. I finish my lesson and by that time I'm incredibly stressed out so I just cry on the couch while my brother has his lesson. After lessons I always have to take a nap because it tires me out so much to do this. Then I practice for a while and by the time i'm done I'm in a really bad state and I just lay on the floor and can't get up, at least for a while. Then I do homework but I feel this way the entire time and go to sleep like that. I forget to brush my teeth or shower, sometimes, and I don't eat a whole lot and try to avoid eating with my family, especially when they go out. I don't want to be around them because I don't like them a lot, don't want to be around people, and want to get work done. I just eat for a few minutes by myself and that's more than enough.

Notice I've avoided saying the words depression here (although I used 'anxious' I felt I had to). One thing that gets me all in a knot is the fact that I'm denying I have anything wrong with me unless the extreme happens in order to confirm it. I won't be getting any diagnoses-- I will not ever tell my parents. They can't know nor do they deserve to delve into my personal affairs. I love them but they will not know. The only person who does know is my boyfriend, who also struggles with these problems, among others. He's been my help through this. I'm afraid to tell anyone else like my friend or sister because they'll probably think it's stupid or they'll just diminish it by saying 'yeah, me too, everyone feels like that' or 'I'm so depressed haha.' Like it doesn't matter. And I feel as if, since I'm not diagnosed, I cannot tell myself or let myself say that I have a problem or problems. I don't want to be one of those self-diagnosed idiots you find on the internet freaking out because they felt sad once, like the rest of the world definitely has. So part of the reason this might be so bad is that I've been telling myself I'm a fake and it doesn't matter. Because it doesn't.

I also have a history of OCD but I got rid of it myself as a child without knowing I was treating myself (also undiagnosed, because maybe my guidance counselors didn't feel the need to say anything. They questioned me a couple of times and were pretty concerned...). I feel the need to apologize a lot so maybe that's remnants of it, I don't know. I'm also scared it'll come back because I know it's known to do that with some people.

Basically, I could go on about how I hate myself and a million other things. But that's the gist of it. I realize that I didn't really organize my thoughts at all so I'm sorry if it's really all over the place and not comprehensible.