Seeing everyone's ages make me feel old at 26. 

To the OP, ​you do say you have some friends. Really, all you need is a few good friends and your family. Once you leave secondary school and university your friendship group will often fall to a few good friends anyway. The world of secondary school, with its cliques and large social groups, is not really like the rest of your life, in my experience anyhow.

 I do get the slight impression you are measuring yourself against a contemporary ideal of popularity and success with women. This ideal is not only dubious but it is conflicts with your philosophical and religious perspective. Unfortunately, many young men today measure themselves on how well they do with women, even if most do less well than they'd like. You should try as far as possible to not measure yourself in that way. At eighteen it really doesn't matter if you don't have a girlfriend or have never had one. I won't lie though, if you do want to try to meet a girl you will probably need to work on your confidence. Courting is a strange thing. Sometimes you can just meet girls who take a liking to you and it takes little effort to start dating and seeing if you could marry. But often it takes effort on a guys part to put himself out there. Unsurprisingly perhaps, women in the age of feminism still expect guy's to do most of the work of initiating, and showing confidence in doing it, in the early stage of courtship. 

Whilst it is true that you can go to a party and not do all the things you mention, I must say parties won't be that fun if you aren't drinking, not for more than an hour or two anyway. Much of Western social culture is built around drinking, and it can be a bit of trouble if you don't want to drink. Going to the pub, to clubs, and often to parties is less fun if you are not drinking and certainly it is hard to do for the usual length of time. I don't much like the BBC in-crowd of comedians, but I remember a good small section by David Mitchell on just this issue, which I managed to find. I think he gets it right:  




My advise would be to go to the party and enjoy yourself (maybe have a cup of coffee or two, if that is your thing), but don't be afraid to leave after an hour or two if you aren't having fun.

 Are the no friends you can make at your mosque? I have personally missed out on this, but friends, especially ones you can meet regularly in real life, who share your spiritual and religious commitments are great supports. You are a bit young, but if you want to meet more people you can always join clubs or hobby groups. There are even online meetup groups and that sort of thing. I joined some of the latter for language conversation pratice, and they can be good.