Don't tell her that you love her.. Be slowly with it. Say that you like girls and all that stuff, then ask her for her sexual orientation. If she likes Girls, too, then tell her that you love her, if not, ... :-/ good luck ♥
Honey, I was in your same situation 3 years ago. Now the girl who was my best friend is my girlfriend and we love each other more than anything.
Personal experience: keep loving her, keep trying to show her your love, because I think she loves you just as you love her. Tell her about your feeling, show her she's the only one for you. She will demonstrate you that she feels the same :3
Be ALWATS true to who you are, go ahead with everything, we don't know how much our time would last, makes everything that makes you happy don't hide nothing inside you baby :)
maybe you can ask her what she thinks about lgbt in comment, if she's okay with that, you know she wouldnt make a problem if u tell :) but i completly understand you tho