Idk :')

Okay so I have a girlfriend and I've always been loyal to her, we've been going strong for almost two years now! But the issue is I've always wondered if I'm poly and honestly the thought of telling her about me questioning myself on this terrifies me. I really started questioning myself on this about a year ago when I first met my online friend Brandon. I ended up having a crush on him even while I loved my girlfriend, that's when I started looking more into poly stuff and trying to figure things out. Eventually, he left the community we were in together so I was able to forget about him for a while until he came back sometime this year. Again I developed a crush on him and really started to like him again but still, I was with my girlfriend and loved her a lot. He was a huge part of this questioning journey I've been on for a while now. I doubt I'll ever have the courage to talk to her about it but I know she's a very understanding person and would at least hear me out. I don't know if I'm 100% polyamorous but I question myself a lot on it. I hope one day I can figure it out, and if I am poly I hope she'll accept me for this too.