I (17m) have a girlfriend (17f) but caught feelings for another girl recently.

TLDR; I have a girlfriend now but I might want to leave her for another girl. is it a good idea?

My girlfriend now, let's call her Stacy, and I have been dating for about 1 and a half years now. However recently I have been getting closer to another girl we can call her Lisa and I just don't know what to do.

Stacy and I have a great relationship and we are planning on going to prom together this year (junior prom at my school) and I feel like I love her but I'm not sure. whenever I'm with her alone I feel like we can never just hang out and talk about things like normal friends / gf/bfs do. there's always this mentality of there's nothing to do so let's just have sex. I am often very bored when hanging out with her. However when I hang out with Lisa I feel like I can just really get close to her and her family is so fun to hang out with and Stacy's parents are PSYCHO (she is an only child) so I just do not know what to do. Also, Stacy and I have some overlapping friends but that is mainly because I am friends with them first. she is a very quiet girl but she comes out of her shell sometimes. While Lisa and I are in the same friend group and that's how I've gotten close to her.

I feel like Stacy is a great friend to have and she is a nice girlfriend but Lisa is like a best friend to me and I want to take our relationship to the next level but I'm nervous that she might not want to and I will be throwing away the other relationship for nothing. What I'm trying to figure out is... Is it easier to fix what I already have or start all over again?

edit: it is 1:04 am I can't let this shit keep me up all night. I will respond to the rest tomorrow. thank you all