i'm stuck between desperately wanting a social life and rejecting invites out of fear

at least once a day i get taken over by an intense feeling of loneliness even though i have a fair amount of close friends. we all hang out together, but each one of them has their own group of other close(r) friends and i'm the only one without, so we aren't really this group of bestfriends, but whenever two of us plan to see eachother the rest get invited to join as well.

anyway, problem is we've only hung out twice since summer's started and it's partially because of me. on one side they're busy with their other friendgroups, on the other side i never text first, never take the initiative to make plans, and even when someone else does i find a way to not go. truth is i'm scared they'll think i'm too "clingy" or "lonely", so i feel like whenever they invite me anywhere it's out of pity cause they know i have no one else.

three of them are supposed to be coming over tomorrow, but i feel dreadful now just thinking about it. i think about how they'll ring my bell and i'll have to go open the door with a big smile on my face, how i'll have to keep that smile on the whole day even if i've been anything but happy lately, the small talk and the gossip and stupid jokes about the same stupid people over and over and over again. i have no energy for anything or anybody.

i cry and complain about not ever getting out but when i actually can i want to stay in (knowing i'll regret not going). it's always like this, sometimes i push through by actually showing up and i end up having a ton of fun, but then time passes and i start to feel lonely again and the cycle repeats. i'm desperately trying to be better. if anyone else has felt like this, please let me know. advice is also appreciated :)