What are some signs my friend like me more then just friends?

im not quite sure if im getting mixed signals or not ?? okay so this girl I know send me a text asking if I would like to see the new harry potter movie with her and i did say yes ! she told me that it would only be me and her because we never had alone time together and when another friend had asked to come thats what she said ! I payed for the movie and snack! she wanted to see it another time with me and she would pay ! we have been texting alot and most of my texting is from her ! she invited me to her back to school bbq and told my friend about it and said she hopes I can make it and when I said I could she was so happy we even gave each other nicknames ..she tells me how she is felling and gets mad at me when I look at other girls .but she also tells me about her ex and how she still loves him ... I dont know but sometime I feel she likes me but i.m not quite sure help!