If you are over rotating it could be from a couple different things. First, on your attempts, how are you approaching, are you edging hard and fast? Second are you getting very high? If you are doing low and fast spins, then you need to calm down on your approach, you can do this a couple ways: First you can take a long easy cut and just have a long approach having a very slow progressive edge. Allow your board to follow up the wake and relax in mid air keeping your handle close to your hip. Try to blink either right when you leave the wake OR at the apex of the rotation. This way your eyes are OPEN on your decent. Believe it or not, keeping your eyes open is prolly the 2nd most important thing in this trick.
The second way you can attempt to fix this trick is to go out about 10 feet from the wake (about where the side spray is), then take a good progressive cut towards the wake. Again allow the board to follow the wake all the way up, relax in mid air, and keep your eyes open.
Believe it or not, if your approach is fine, then you should think about your body position in mid air. I say relax in mid air, because most often then not, you are so tense from trying a invert that you go ridged in the air, not allowing your body's muscle memory from a regular wake to wake landing to take over. If your board is hitting the water and it just keeps on rotating and you slip out, then you need to relax a bit. This trick you dont have to force anything, it is a simple fluid motion all the way up and down. There is no 'hucking'.