I agree with Ken.
Putting you straps more inside will have little or no influence because the back foot needs to come out anyway to push the downwind rail towards the water. My front foot (that stays longer in the strap) helps me "pulling" the board leeward.
Especially with a formula board, where the footstraps are extremely outside positioned, this pulling technique helps me a lot to carve through the jibe. Fantastic feeling, I always find.
If you round up too far, it's almost always caused by flipping over too late, or bad flipping over. Many people make the mistake that the mast is gettig too far away from the body, during flip over. After flipping over it looks like they still still need to "uphaul" the rig, sorts of speak. Then it's also normal that you round up too far. At the flipover moment, try to pull the mast ASAP towards the body. Also holding the mast with one hand just above the booms helps in fast flipovers.
I know that this tip has improved my jibes a lot.