Theres this girl that follows me EVERYWHERE she waits outside my door!!!!!!!!!?

shes 9 and i am 13? she will wait outside my clroom door til i come out. i will go to recess and she will talk and talk and talk and play whatever i play. like today i was playing soccer and she came up and talked the whole recess. i told her that only 6th graders could play and she said it was o.k if she played. she is sooo annoying. i feel bad for her , because she has NO friends. what should i say to her to have her stop following me? nicely though cause she is only 9.. HELP i am losing friends because they think i am leaving them for her as my bff!