How do you know if you like someone?

I don't know if it's a crush because everyone always says you get butterflies and stuff around your crush. I asked for advice and I received an "it's not a crush" so I'm really not sure anymore.

The thing is, though, I really do like talking to this person and I think about them a lot. We talk almost 24/7 and they're quite touchy with me. I never feel butterflies but I want to be closer. I don't know if I'm tricking myself or what. Also, they recently told me a story and when they mentioned that they got really close (physically) to another person, I felt annoyed. Is that possessiveness or jealousy?

How do you know if you like someone? What are some signs?

Edit: So... they keep giving me hints that they like me and I've been so blatant about how I "like them" but I'm genuinely so confused about how I truly feel. Is this a crush or just attraction? I really, really do want to like this person because they're so sweet and affectionate and cute and amazing but I don't know if I like them.

Edit 2: CONFIRMED. THEY LIKE ME.