It sounds like you have a little bit of social phobia. I often feel that way myself. Do you find yourself worrying about things you said afterwards? Do you worry that maybe it didn't come out exactly right, or worry what others might think of you or something you said? You can drive yourself crazy analyzing yourself and the situation after an event with people.
Since I am rather introverted, I always feel more comfortable getting the other person or persons to do the talking. The best way to do that is to ask questions of interest. Talk about things in their life and then try to remember what they said. That way, when you see them again, you can remember something about them and start your conversation there. It's sort of like picking up where you left off.
You have friends and you have a boyfriend; so you must be doing something right! Try to focus on those positive things instead of worrying so much about how you come across.
Diagnosed with: seizure disorder in 1962; seizure-free since 1969, anorexia from 1968-1969; IBS-D in 1996, Mild depression, anxiety, & OCD in 2000, (probably had since childhood); PMDD in 2001, Dysfunctional tear syndrome in 2009; Meds: Phenobarbitol, Paxil, Allegra; Supplements: Citrucel tablets; many vitamins, minerals & herbs - too many to list here