Because I've never had friends for most of my life, I've developed some very deep insecurities and esteem issues. What I mean by assume is that many times I'll make up in my mind a reason some girl rejected me. This keeps happening to me in college.

For example, I'll talk to a girl in class/cafeteria/dorm and make small talk with her. I'll eventually ask for her snapchat or number after a few days and about 65% of the time I will get it. However, then about 95% of the time when I hit them up to hangout or do any activity on campus, I get a "I'm busy" or no response at all. I then assume it's because they gave me the contact info to save my feelings and found me to be too skinny/not muscular enough, facial features too weird, etc. Any tips?