My first piece of advice: don't put too much pressure on yourself to decide on your label! Sexuality and sexual orientation is complicated and fluid. Explore your options in a way that is safe for you—I don't know your environment or circumstances—and at a rate you feel comfortable with. That might involve just chatting with other people in the LGBTQ+ community, especially if you can find and reach out to other people who might be bi or questioning. It helps to know you're not alone and hear other people's experiences. You might decide you want to try opening up your dating pool, or you might decide you're not ready to get that exploratory yet. There's no wrong way to approach your identity, though many people may try to tell you there's only one right way. (Hint: those people, however well-meaning, are wrong.)
My default response to something like this is, do you actually need to do anything at all? Having feelings for someone doesn't require any activity unless you *want* to act on those feelings. Sometimes we can feel very compelled towards our friends and it can become confused with romantic feelings. This is, in effect, a crush... There's no need to act on it, to "come out" a different sexuality, or anything else. That is, unless you want to. I'd suggest that you wait it out, consider how your feelings evolve, and then decide if it's one of life's random crushes or if you really are looking at an orientation change. If you decide to act on those feelings, know that they are completely normal and that the best thing you can do is act with respect, for both the object of your affection and yourself. If you don't want to act on it, that's perfectly fine too.
Labels are for you to decide what fits best for you :) You can be attracted to someone of the same gender and not necessarily be same-gender attracted generally apart from this crush. You're allowed to change labels- nothing is set in stone, so if you feel comfortable identifying as bi, then you are- if you aren't comfortable with bi as a label then you don't have to use it. You're the only person who gets to decide what or who you are. As for the attraction for this person, consider analysing what is it about them that attracts you in order to understand it and therefore you better :)