10-15 7.5 125 should just ok. For 72 115 can be a bit much depending on the rest of your quiver. Did you check my gear calculator ?
windsurfing.lepicture.com/tips-and-tricks/105 is a good mid size for you. You could do 85/105/125 for a 3 board quiver. I had Formula, 105, 77, was perfect!