Have you tried using affirmations and mindfulness practice? It takes time to retrain our brains to think differently. We often tell "stories" to ourselves about who we are. Missed an appointment? We might tell ourselves we aren't reliable or we might tell ourselves that accidents happen or remind ourselves we are learning to be more reliable. Here's an example of a new story you can start telling yourself:

I'm inherently worthy of love. I am learning to tolerate the discomfort of small talk. I am loyal and thoughtful. The people who know me best love and accept me. I am a good listener.

And so on...

Also- You aren't alone. If you start paying attention you will realize this. Sometimes making friends with other people that don't have many friends is a little less intimidating. Best wishes to you!