What should i do about this diffrent girl?

i liked this girl for 3 years abd shes in 8th grade and im a freshman. i recently went out with her a few times and we always ended up makin out, i asked her to be with me she said no. now im going on this final date with her in a week for ger to decide if she wants to be with me.. i really like her but im thinking she wants other guys besides me what should i do?