Love or Friendship ?

Well I'm a lesbian and I have a huge crush for a friend of mine. I think about her all the time and because we're friends so we go together for coffee, movies e.t.c. Lucky me. Thankfully we are not alone, just the two of us, but we have some common friends with us, cause I couldn't handle it. The thing is that I think she likes me too. But then think about it again and try to convince myself that is just cause I like her, that she doesn't have romantic feelings for me. And then it comes my biggest nightmare. She wants me to help her with her math exams(yep I'm a geek whose good at math and likes it too :P ).We will be completely alone , just the two of us. And here comes the big question : Should I reveal my feelings and risk our friendship and my social life (I'm not out as a lesbian yet ) or keep my feelings for myself ?