Okay, I meant to write I believe you CAN find someone. Sorry.
If you're doing the exact same thing over and over again and expecting different results, then yes, that's insanity. HOWEVER, this is not like that. You can do the same things over and over, but you are who you are. You can change who you are. Now, unless you're trying multiple times with the same woman, you're going to get different results. Different women react in different ways. Sooner or later, you will find one who appreciates you for who you are. That's not insanity. That's trial and error. That's life.
Now, here's the thing. I think you're thinking way too much about your own mortality. Yes, you will die. As will I. As will my girlfriend. As will all of us and our girlfriends. However, you are 21. I'm 19. Both of us have no reason to be considering how we will die. And yes, I was serious when I said you could die from being alone. You seem to be reacting very strongly to the fact you are alone, even swearing that you refuse to die alone. That right there shows that you are stressing yourself out over this.
Relax. Live a little. Accept that you will fail sometimes, but sooner or later you will strike gold. Finding the perfect woman for you is not an instant process. It takes time, effort, repetition, and some luck.
As for how I can't imagine how you feel... no, I can imagine. I can imagine a great deal. I've been through this. Many people have. It's natural. The trick is not letting it get us down. You claim that you can easily find confidence in yourself. Show me that. Right now, I'm not seeing confidence.
Either way, I'm just offering my advice for your situation. I'm sorry you have the condition you do. All I can say to that is that while I may not be a doctor, I don't think working yourself up over your love life is good for your health.