I love my friend but is she using me?

My friend has a b/f. I told her I really have a huge crush on her and she said she is only interested in being friends and that i am very charming. I do stuff for her all the time. She always hints at stuff she wants me to do for her. The other day she was really craving skittles so I went to 3 different stores to find them for her and she was so happy I did. She was telling me she wanted to clean her car in the washbays at work but it was too cold and she was saying it like she wanted me to do it. Then she wanted me to move her car for her cause it was cold out. This stuff happens all the time and I usually always do this stuff for her but it gets me nowhere. What should I do? Should I just walk away for a little bit and see what happens.