I started the game less than a week ago because of Legendary Days (I like GH more) and I'm level 13 and I got her only after some 20 tries (I thought I wouldn't since I don't even have max combativity yet (it's only 12) and I'm barely into the game with only 2 girls other than the 4 which game provides)
So don't give up.
I might be incredibly lucky but there are still a few days left and you just might win her!