So sorry you're going through this. If I left it to my ds (year 7), he wouldn't socialise with any of his school friends, he'd just see his village mates who all go to another school.
I think you're going to have to take charge of his social life by inviting maybe one child per fortnight after school for tea, or for a Saturday afternoon. They'lll probably have a great time once it happens, but maybe your son worries that if he invites someone directly, and that person can't make it/doesn't fancy it, he'll feel rejected.
I tend to phone the mum, organise it then present it to my ds as a fait accompli (I do check, first to make sure they haven't fallen out or anything).
My experience, however is that there just isn't the same social life at secondary as at primary, where the house was always full of children. Partly that's just because the secondaries, certainly here, have kids from a 15 mile radius so parents can't always be bothered with all the driving.
So far as the "annoying" thing goes, my ds says that about quite a lot of people as well. I think at this age they're much less tolerant, more fussy about who they'll be friends with, but if you can get them together one to one then I do think it helps with the in-school relationships.
I recognise the "not enjoying anything " bit as well. Sometimes it feels like no matter how hard you try, for example to give them a really good, fun weekend, they don't appreciate it.
Have you thought about maybe approaching the GP? These days lots of kids get depression at this age and the GPs aren't likely to dole out pills, but may refer him to a counsellor who may help just by being a sounding post.
I do hope things improve. It's a bloody rocky road at the moment, you are not alone!