I thought this part of my life was over

I've always been a socially awkward person and I had very few friends growing up. Nothing made me happier than entering my 30s and suddenly no longer having the societal pressure to go out and party and meet new people, etc.

Then my son turned 1 and at his first birthday party (a casual, outdoor thing at the local playground pavillion) there were so many no-shows of people who said they'd come that I was left with mounds of pizza, a barely-touched cake, and a crushing sense of rejection and embarrassment. I know my son was too young to notice or care, but I noticed, my husband noticed, and the few people who did show up noticed and looked visibly embarrassed for me.

I thought I was done with being a "loser" with no friends, but I'm right back to feeling like I did throughout my teens and early adulthood. Now my son is about to turn 2 and my husband keeps asking who we should invite to his birthday and I have to tell him bluntly "I don't know, I haven't formed any relationships with other parents and because of that he has no friends."

I want to cry. I thought this part of my life was finally over but here I am again after all these years. Sorry, I just wanted to vent my anxiety and feel sorry for myself out loud.

(To be clear, my husband is an awesome dad and partner, and the only people who showed up for the first party were his friends and family. I'm a SAHM, which is why he's asking me about who to invite from my non-existent social group.)