I've been in the same situation in the past but, oddly enough, I feel like that experience has made me less worried about making friends in vet school. Obviously I do want to make friends, and I am nervous about meeting new people and making a good first impression, but I know that even if I don't make any friends at all it won't be the end of the world. Been there, done that. Actually having friends is the vastly preferable option, of course, so I will be doing everything I can to make at least a few. But I find it comforting to know that I'm independent enough to survive four years entirely on my own, if it were to come to that.
My problem is that I'm really not one to intrude on an established group, no matter how new it may be. So when cliques spring up like wildfire during the first few days in a new situation like this, I usually end up being the odd one left out. 🙄