Sometimes people with the schizo family of disease have trouble recognizing basic social cues like facial expressions much like in autism. There are online tests you can take to find out if that's the case for you.

I too have trouble making friends but tested average in emotion recognition so there must be more to it. I went through a course of CBT and that helped me overcome a lot of self doubt. My therapist told me to try craigslist, strictly platonic. Its an easy way to start. I've met about 6 people this way but only one of them is what I'd call a friend so don't expect magic, there is still an element of chemistry that's unpredictable.

What I've found I like even more is meetups. Here you interact with a group of people, some are regulars and some are random and then you do an activity which can be anything you like. I'm in a movie and food group because who doesn't like movies and food!

Anyway, its not just you, good luck with finding friends!