I'm not sure if it will help, but at some point I believe that you need to just give up on the expectation or anxiety of finding someone. Have you ever gone to bed with the thought in your mind, about "I hope I don't have trouble sleeping tonight", then end not sleeping all night? I believe that whether you realize it or not, you are likely going to clubs, parties and such with a "negative vibe", meaning that you probably are there actually expecting to not find someone.
A good example is my wife who recently "gave up emotionally" on ever getting the child support she is owed by her ex-husband, basically saying I don't care and I'm not going to try going after him anymore. Literally one week to the hour later, she received almost the same amount of money in disability compensation.
You can call it karma, fate, the interconnectivitiy of the universe, or whatever, but sometimes you get exactly what you are asking for, even if you don't realize you are.

I know it is hard, but you need to put effort into NOT being jealous of others, or into NOT expecting to find a partner or friend when you go out. It will happen when life is ready for it to happen. You've made a habit out of being disappointed, and now you need to break out of that cycle.

YOU CAN DO IT! I know you can!