I feel like a loser

I'm (24F) a social failure and a failure all around for my age. I've always been bad at socializing but I excelled academically at least. But after high school, I couldn't figure out what career to study until little ago so I'm late now compared to normal people.

For context I'm diagnosed with ASD and OCD. It was hell on earth these past few years and the pandemic didn't help. I'm just so late in everything. I haven't ever been in a relationship either and I'm getting desperate. I must be too ugly or weird. My younger sister already beat me on that. I think it's because I'm overweight now after struggling with my mental health years ago, my BMI is 27. But.. even when I was thin no one was interested in me.

It sucks because men on social media keep talking about women hitting the wall by 30, or even 25. I'm just doomed. What's the point of looking forward to birthdays if I'm going to be an old hag nobody cares about? I always advocated for not generalizing anyone, but after being sister-zoned IRL and reading men's opinions online, I'm beginning to hate men as a whole. And couples. And neurotypical/pretty women, too, for having it much easier than me...I'm hating everyone.

I know it's wrong but I can't pretend I'm happy.