How do I tell if I like someone, want to be their friend, or if I am just romanticizing the idea of them?

I posted a thread on this forum literally a few minutes ago and it is sort of related, but I felt this should be its own thing.

Recently, I've been having trouble determining if that pull in my chest when that special someone walks by is from me having a crush on them, romanticizing the idea of them based on what I know about them, or if I just really want to be friends with them and that pull is just me wanting to form a bond with them. I wish there was a little thing that told you because things would be so much easier.

 I don't think I can go another day having the cool bass player in my guitar class compliment my outfits because I get nervous when he does it and don't know why. I'm not like this with other people, just those I want to be close with. I find myself wanting to strike up conversations with him, which is odd because I don't like to do that and I'm effectively mute in that class since I'm not friends with anyone there nor is there much of a reason to talk in that class. I'm scared that it might be weirding people out, which I already do since I have terrible RBF, I'm very straightforward, and I'm very open about my extremely weird interests such as oddities, shows I like, and novels.

Long story short, how do I figure out what I'm feeling and stop accidentally being weird as hell???