2008 zx190 setup help

Got a 2008 skeeter zx190 that is running 55 at 5900 rpms WOT light-medium load and 2 people. Seems like it planes fine and holeshot is good, but I feel like top end should be better. Prop is the stock Yamaha 23m. Steering feels a little stiff at higher speeds. Stock 12" jackplate shows 5 dots trying to figure out prop to bad measurement but don't want to post it and throw off input because I am not sure if it is right. Any input on adjustments to make or if I should go up to a 25m prop, or possibly get this one worked and pitched up to a 24?

You're about where it's going to go. You might drop the motor a bit and see if you get some lift, but you can't turn a 25 with a 150 on that hull.
So...go down until you lose speed, then you'll know exactly where the right height is.