I do, but I'm still treated like everything is fine and my lack of enjoyment in activities and social success are attributed to personal failings rather than a need for medication.
I'll spare you my cynical opinions about dealing with doctors, but I will say that sometimes you have to say, "no. I'm not okay. I am in a terrible place and although my attitude about it before has been passive and cranky, I'm willing to work on this, and I need you to hear that it is not working just to have a Xanax as needed. Yes, I am also committed to working on my outlook and won't just dismiss things or quit."
I've had to argue with a doc before to try something he was skeptical about. I brought studies, lol. He reluctantly agreed, went silent when it worked, then when I no longer needed it after a year or two and said so, he (whom I otherwise like) kind of smirked and said "didn't think so.". But he was wrong, because it did exactly what was needed - to the point I no longer needed it. ...anecdote is not to say fight your docs, but that it's fair to insist there is a problem and they need to pay attention. But you must do your part.
I don't really know how to do any of that though, how do I just become passionate?
Well, since you can't think of anything you like, I'd say it's just a
decision. Pick something and pursue it, throw yourself into it. It can't be games or anything involving a screen, because that's too passive. And it can't be girls, because you don't have control over that.
Decide to learn about & start collecting coins; or learn about Baroque music and find a favorite composer; or read the pulitzer or Booker Prize shortlists from the last year; or learn about some old wars and set up miniature battlefields - you could even learn to paint the figurines (not necessary); or learn some card tricks; or find a pool, learn the breastroke or backstroke and start going - one length to start then start setting some goals for times/ week or laps or technique; or get a couple plant pots, get the right soil and nutrients, and see if you can make something grow; or take a fencing class. Whatever. Or just start exploring the area where you live - paths or trails that take you somewhere new. Try one thing and if after 3 or 6 months (yes, months) you don't care about it, try another thing. Or if you care a little bit not a lot, add on some other thing. Etc. You need to exercise these mental muscles. Always hard to start, but like at a gym for physical muscles, they get stronger.
If all of that seems like too much or too confusing, just go for a walk or bike ride. Go a place you haven't been. If you see a nice place to stop, stop and sit in the grass. You can leave after 5 minutes if you're anxious, but next time stare at the trees and the clouds and empty your mind of any wordy thoughts for 10 minutes. Take a notebook and a pencil even if drawing seems boring or you're bad at it, but try it anyway. You could draw a landscape or a leaf, doesn't matter. Or write down the words in your head, no editing. Do it a number of times. It might bore you/ not trigger any interest - but it could, and either way you've done something with your time that is better for you in every way that sitting in a room.
Most people don't have a single, overwhelming grand passion, but finding things you enjoy - and putting enough time into them to make them become something comfortable and that you might look forward to doing - is a good way to round out your life a bit. (Which not only may make you interested in stuff but also makes you a more interesting person.)
I'd probably just spent most of my time trying to appease her and keep her from leaving me.
Yeah, so you're obsessed with something that you really don't have any idea what to do with even if you get it. Do you see how this is all out of whack? Not that anyone knows what to do with a relationship before they have it, but you just described a very bleak and self-oriented perspective.
And also, a relationship with someone spending all their time trying to appease and keep you from leaving sounds very unpleasant and exhausting. This is why people talk about "you need to bring something to the table." People are attracted to people with something going on beyond "I just want a girl/ guy.". Most people want to enjoy time spent with another person - which is hard to do if that person is a blank slate with nothing to share and nothing going on but desperately trying to twist and turn to have A Relationship.
Internet randoms that respond to my cringe "need pussy" rants, and by pretty directly just saying that I seem like I would be abusive if I ever got a woman.
Oh. Well I'm guessing they're basing that on your cringe comments and certainties about how people/ relationships are. So it's a comment, not a prediction. You own what plays out.
Usually doesn't get farther than asking each other how our day has been and making some small talk before she stops replying. I don't know if I need to be direct with my interest in her or what.
Have you tried sharing something neat about your day? Get excited about your own life, and you won't bore someone to tears!
I usually don't get anything to eat(I have dinner before class to save money) and when I have I've gone alone usually I just take the time to get my dating swipes done(if I didn't already) and to work on homework.
Great, so you have all the power to change this. Take your meal to school, go eat it outside nearby or maybe eventually you'll connect with someone else who might want a meal. Don't bury yourself in your phone. At minimum get a book and do that instead. Keep your eyes up off the ground in general and make eye contact with other students, even if just for a nod.
Lord. Everything people toss out is not a literal reality 100% of the time. People were saying that, generally, being desperate isn't a good starting angle. 
