I'm a girl. I have a crush on my female best friend and was wondering how can I find how she feels?

That is a major problem for this generation's youth with the way environment has become. Kinesics is an artform, and with sufficient mastery one need not have been direct in their manner of inquiry to sense people's true feelings (hon-ne), current mood and personality. Subcontext can be distorted and scrubbed to a greater extent, for the most part even completely left out without the time put forth to introduce it.

What you should do is consider the extent of what you know objectively, given your years of acquaintance. How does she feel about this type of relationship, how often do you hang out, what's the nature of your current interactions, what kind of unusual signs has she given you, how badly might she flip out, what's at stake.

Other than that, sometimes you just need to try and see how it goes. Failure builds confidence if you don't let it get you down. And sometimes a crush is just fleeting and it's preferable to focus your attention elsewhere.