I have two questions 1) am I bi? and 2) does this girl like me?

Hi sorry this is my first post so it might be a little insane. I have two pieces I need advice on so I’m going to split it into two paragraphs.

I (22F) have always thought to be straight because I’ve only had romantic relationships with guys. I’ve always thought certain women were beautiful but tossed it to the side because girls are always like ‘oh my gosh you are soooo pretty’. Never thought anything of it. That is until Emma. Emma (21 F) is drop dead gorgeous and incredibly sweet. It wasn’t until a male friend and I were talking and he mentioned how he would date her if she wasn’t gay. At that moment I questioned how I thought of her. I’ll admit I got a little jealous at the thought of someone with her, but I would still be happy for her. I’ve thought about if I could be and the answer is maybe, but I don’t know. I don’t think I am because this is the only girl that I’ve ever considered dating but I dunno. What am I? Am I bi?

Second point of intrest I think Emma is flirting with me. We both go to the same college and I have two classes with her, plus we’re in marching band together. She’s in color guard and I in low brass. Whenever there’s a break in class or band she comes over and talks to me. And when I talk she just smiles, looks at me, and nods. I don’t know if she’s just listening or really listening. She laughs at any jokes I make and it seems is either talking with me or standing around me. Emma doesn’t really have a flirty personality from what I’ve known about her. She hasn’t done anything out of her way to hang out with me it’s whenever I’m doing the same activity as her she’s with me. I also told a mutual friend about this and she said Emma didn’t like be. My counter argument to this is not everyone tells their friends when they like someone. Plus Emma and the girl I asked aren’t very close, I asked her because I trust her the most out of our mutual friends. Is she being friendly or flirty?

I could just be insane but I need opinions on this. Thank you so much!!!!