I dont know if she likes me

so there's this one girl that I share multiple classes with. we're not best friends or anything, but when I love talking with her when the chance arrives, its always the highlight of my day. more recently she's made it a bit of a habit to tap on my shoulder when she's passing by, and we exchange a smile. I'm honestly not sure if she's trying to send a message, I've never had this kind of interaction with a girl. if she's just being friendly, I'm more than fine with that and as i just like spending time with her but it never has to turn into something else, but I'm just not sure if I'm being stupid and not picking up on a sign, or if I'm just way over thinking it. I'd ask her directly but I'm nervous that she'll think im creepy and she'll stop interacting with me. am I overthinking this?