That can be really tough; I've had similar experiences and I'm sorry to see what you're going through. You are not the only one (there's an article above with the data!). I hope some of this helps; f some is way off base, ignore that part:
Most of all, have compassion for and care about yourself. It doesn't solve every problem, but it's the most important relationship you have by far. Without it, you'll always be lonely no matter who is around. With it, how others respond won't matter so much.
Have compassion for the other people too, especially those who don't respond. They have their own problems which have nothing to do with you, which, like everyone else's problems, might make them a*holes at times. The reasons they don't respond likely have nothing to do with you. Don't objectify them - don't make them characters in your narrative of your social life; they have their own narratives independently of everyone else.
Another reason to have compassion for them is that people in your situation tend to adopt a perspective where all the power is in the hands of others: They respond or they don't. It's not a healthy (or realistic) perspective; you have power too and they are flawed, vulnerable human beings too.
And more practically, instead of worrying about people who don't seem to respond, keep trying until you find some who do - it can be hard to motivate yourself but it's worth the effort. For everyone, there are plenty of both kinds and it's no shame if it doesn't work out with some - that's inevitable given the odds - or if the ones that will respond are hard to find. You don't need many successes to have a social life and you are worth the effort no matter how bad your experiences so far.
Finally, many people find themselves lonely at times in their life, and find they need only one really close relationship, a life partner. If you have yourself (see above) and a life partner, then the other relationships become much less significant. Maybe that's the real goal; it can take a lot of looking, but once you find the person you both have it made (with plenty of work!).
Good luck!