I had the same problem for years. I would panic that my posts didn't get likes, that meant people didn't like me, or I wasn't as cool with my friend with 100 more likes, or it was because I was fat or ugly or something was wrong with me. I think it took me actually loving myself to realize it's all BS (which is a hard road to climb to get to, especially with C-PTSD). People love me and I love them and most of the people I love aren't even on social media. And just because someone likes a post doesn't mean they don't think I'm weird or annoying or whatever lol.
This is probably REALLY bad advice but....here it is. I just started posting whatever the hell I wanted. I posted whatever made me happy. I posted art I made. I posted rants about mental health. I posted things I thought were funny. I'd post like three times a week on instagram, sometimes more, I don't really use facebook. My older family members didn't see my stuff like grandparents and all so I had some freedom. I stopped caring. I stopped caring if people knew what I was doing, because honestly other than my family and my immediate friends, I didn't care what people were doing either. I was so sick of seeing picture after picture of posed people "doing something" that gave them status or proved they had a social life. It's the proverbial white picket fence and mowed lawn. Liking someone's picture and commenting on it doesn't mean I like them, or love them, and it doesn't mean I have a connection with them either.
The people who get the most likes play by the rules. The "rules" are that you comment under people's pictures all the time, they'd do the same, and the algorithm would boost their posts. Also, most of the people who commented under other people's posts didn't even know them, weren't actually friends, and sometimes would tell me how much they didn't like those people (but they still commented!!). It bored me, so instead I followed artists that were making cool things and writers and all that jazz. If people think you're weird and don't wanna be around you, then they aren't your people. I had people make fun of me for my art (in person!! lol), but you know what? I just realized they weren't my people, didn't get me and I removed them from my accounts myself. I deleted some of my original accounts for a break and that was nice, and my current ones, one is professional and one is a private account to keep in touch with my family and friends in other countries. Most other people unfollowed my personal bc I probably annoyed them by not playing by the rules.
Everyone I know has anxiety about posting on social media because of the unspoken rules about it, you're not alone. It's like any social game.
Would it help to keep in touch with family in another way? check in with them every so often on apps?