Am I actually gay? Or am I just faking it?

Help I need some advice! Ok so here's some backstory: I'm a girl and I'm 16 and my one older sister is 3 years older than I am and she recently came out to me as gay this year right after we saw Love, Simon. And, I had a pretty good idea that she wasn't straight but I didn't want to ask her about her sexual orientation bc I wanted her to come to me when she was ready. So after this I had to begin to think about my sexual orientation and if I was not straight. Bc sometimes I'd see a girl and think 'wow she is just so pretty' but then I'd think about 'wow I'd really like it if I could hold her hand and take her on dates and spend my time with her' but I guess I would just dismiss it as 'oh I bet a lot of straight people think about what it'd be like to be gay' but I guess i saw this one tweet that said something like "I came out as bisexual to my grandmother and explained to her as 'I like to look at girls butts' and my grandma said that every girl does that then my sister said that no they do not and my grandma said she might be a little gay" and I know that I should not make one assumption about my sexuality based on a tweet but if it isn't really straight to look at girls butts then I questioned that I might not be straight bc I do that sometimes admittedly. And then I thought about how I might really be attracted to girls too, and how I would date someone if they are a girl or a guy. and I thought that if I absolutely had to put a label on it (which I know can be bad)I would call myself bisexual. So after I thought about this I really wanted to go to my sister and ask how she knew she was gay and tell her that I might be bisexual but I can't work up the courage and I honestly don't know if I'm really gay or if I'm just faking bc shouldn't sexual orientation just be something you know and don't have to question? So I'm really sorry about this SUPER LONG post I understand if you didn't want to read it all but I'm just really worked up about this, but what I am trying to ask is: Am I really gay or am I faking it? And how should I go to my sister to talk to her about it?