This is tough love, but no, it's not as hard as it seems at all. That's usually just an excuse not to try harder, honestly. As for not getting a girl interested, that's because of the self-loathing, not the other way around. It's an endless circle, yes, but it can be broken by attempting to break it in the right place, which is yourself. You can get girls by not being self-loathing, but you can't stop being self-loathing by getting girls. It might feel that way but then you're just fooling yourself. And this IS possible for anyone that at least doesn't have serious mental issues that require medicine etc. That kind of thing must be fixed first, then our advice will work for those people too. Anything else is just excuses again. Not being able to go to the gym because of school is probably crap too, a gym session shouldn't last more than two hours, including taking a shower etc. So that's about 6 hours per week. It'll also have a positive effect on your mental health and capacity to work and think so school will be easier if you keep it up. If you have time to argue on GAF, you have the time to visit the gym, it's as simple as that. You can argue with that as much as you want, but you'll only be hurting yourself. As for clubbing, go alone anyway. If you don't, you're again making poor excuses for yourself. You're probably not even that shy, you've just been sold on the concept of shyness. And you're reinforcing the stereotype by telling yourself that you are shy. That's not helping.
I've been down in that depression swamp as well. That's why I keep giving this advice, because it worked great for me and many others, and I'm no longer down in that swamp. Considering you're aware of all the advice given here, you must realize that it's only your own head that keeps you down there, and you give in to those thoughts. Your mind wants you down there, and you let it control you. You can't blame your brain for this, only yourself for letting you be dominated like that. Getting out is actually easier than most believe, and it's only as hard as you want it to be. It is possible to snap out of it like a light switch, but most people don't believe that's true and would argue with me on it, and that's why it keeps being false for most. Granted, I needed my own reality shattering event to snap out of it all and it seems that these are truths you have to realize on your own terms in many cases. Sometimes it's not something you can accept simply by reading about it. I think this thread has proven that many times over by now, unfortunately.
Saying this in here usually makes me feel like the devil's advocate, but I'm very pro creating my own reality. And it always starts with cutting out the shit you usually say, like I'm shy and an introvert, I can't laid because I'm too ugly and fat or whatever. When you say such things to yourself, either verbally, in text or even just in your head, that's the life you will create and live. I used to be as introverted as the next guy but I decided this wasn't true, and thus it wasn't anymore. You gain absolutely nothing positive by reinforcing your beliefs about being shy. But you gain so much by changing that into something more positive like "I'm always confident, courageous and extroverted". Also convince yourself that your self-esteem hole is just a pothole, or better yet, isn't there at all. If you believe that, it will be true.