Openly gay, now bi?

So im 20 and openly gay for the most part, I've been in a couple relationships with guys but nothing super special. I had a relatively quick coming out process even though i doubted about my sexuality for years. I have a kinda quirky but bold personality. So when i met my first boyfriend i got out as quickly, as simple and with as many people as possible. Note that I've also always been more on the masculine side, in fact I'm not a fan of the gay scene. Anyway, after coming out I thought I was done with that dilemma. I've been single for about a year now, I've tried dating a couple guys, they've all been super nice and cute, but I haven't really been able to keep it up, idk why. About four months ago I met a girl thats not only cute, but she's also really nice and I like her personality, i think I might have a crush on her. The thing is, I feel weird about feeling this way towards a girl cause I was so sure I'm gay, that I never really even considered dating girls. I don't know if I would be able to date her, cause I dont even know how to approach girls, I dont know what are her feelings for me, I don't know how well seen it is for a Straight girl to date a bisexual guy, I feel like I would be judged if I told someone that I am going back to girls, I'm not even sure if being bisexual is actually a thing. I have so many questions in my head and I feel like I am going again through all the process of coming out and doubting about my sexuality, im so confused, what are your thoughts on this?