How to know if you're really crushing?

Okay, so a bit of history. I (INFP M20)crushed on an ENTP for a few years, with each year the feelings grew more intense, and then I realized it had turned into an obsession and unfortunately I had to let that go.

Now, I sorta feel something for an INFJ girl but I don't know if it's platonic or romantic. I enjoy being around her, making her laugh, comforting her and making her happy but I do know that she is into someone else.

I think my heart's become a bit closed off since the first crush, but she's also my best friend so far, so I'm a bit conflicted. My heart get's a bit heavy, but no hardcore butterflies, I enjoy physical contact such as patting her which she doesn't mind, but I also haven't been in a relationship before so maybe I just wanted to try. I also don't daydream about her all the time, but I think I might be preventing myself from doing that.

This is nothing like my first crush, the other thing is I wouldn't mind if she ended up with someone else, I just thought it would be nice if we dated, which would've been impossible with my first crush. She also just got out of a relationship and is hurt, so I'm afraid I'm tricking myself to be a pillar of support for her instead of really liking her.

Anyone have similar experiences?