Gidday guys

I have always thought my engine was low but had run out of adjustment. So, I got a set of CMC 5" extensions and redrilled them to give myself a 4" extension. I have now come up 2 & 1/4" and I think I can still easily come up at least one more hole. If the engine is too low can the water pressure on the underside of the A/V plate actually lift the back of the boat and give the appearance of the plate skimming the surface?
Despite coming up 2 & 1/4" already my A/V plate is still not clear of the surface so my engine must have been way low. Like I said, I am wondering if my plate has been holding the back of my boat up all this time.

Look forward to some opinions.

Thanks guys.