Your sister doesn't hate you, you probably just irritate the crap out of her, which is entirely natural and common. If you move up to her grade, give her a lot of space and pretend like she's not there, don't worry about it and enjoy everything you can, focus on the good. If she pokes at you and causes problems, tell someone, don't do it back, and go back to ignoring her and going on with life. She'll probably get to a point where she sees being mean doesn't work, and years in the future you'll probably get along just fine.
MY SISTER HATES ME AND I MIGHT MOVE UP TO HER GRADE, SHOULD I BE WORRIED?