Why can't I make many good friends?

Ok so I have never really had a best friend in my life I've always had a lot of "friends" people who I know and would say hi to if I saw them but never anyone who I was really close with. I've always moved around growing up I went to 13 different schools up until high school (I went to the same high school for 4 years) but I never had the same people in classes I always took classes that were a few years ahead so I was always in classes with seniors who already had a group of friends but would eventually become sorta close with them just to see them leave at the end of the year. So far after 1 year of college I'm sorta in the same situation where I'm really ahead compared to people my age like all my classes are junior or senior level classes so I'm always the only freshman and I tend to know a lot of people but never get the chance to get close with someone because they always leave before we get close. I really do try to be friends with freshman and I seem to be friends with them but not great friends like I never get invited to things they do directly its always through someone else mentioning something going on. I always been told I'm very easy to get along with through high school I never had a problem with a single person and was always very involved I played football in hs but I figured thing would change in college but IDK what to do to make a good friend?