I believe that frank words are always the best solution. Believing someone knows you have feelings for her by the way you act around her is not something you can really trust, since you assume something you never actually discussed with her. She might know, but might as well not.
Having a good talk with her is your only real chance to clarify this situation, although I know it is not always simple to take this step. But you will surely get the real answers. You might want to invite her to some calm place you know and feel comfortable to discuss. Being honest, even if it can hurt you, is one of the simplest steps.
If you still don’t feel comfortable enough to talk with your friend, you might also try meeting a social worker who can give you good starting steps and ideas to open up to you friend and discuss with her.
I hope this helps,
Inge Rollin, Sexologist B.A.