What should I do about this girl?

Ok, there is this girl I have been into for some time, but lately I have started to get closer to her. She seems to be getting closer to me as well. She always sits beside me, or asks me to be beside her. We have been going to some competitions, and when they are announcing winners, she grabs hold of my hand with all her strength. She also rests her head on me frequently and even fell asleep on my shoulder during two car rides. I am not sure if we are just developing a deeper friendship, or if she is into me as well. We have been friends since we were about 5. During the school day she either follows me, or tells me to wait for her. I am just afraid that if I ask her what her feelings for me are that we will lose the friendship that we have both established with each other. I honestly feel that I may love her. I have never felt this way about a girl before. I am not sure what to do. And if I do make the leap, I wouldn’t know what to say to her. Any suggestions?