What I have noticed by watching many bowlers over the years is that forward finger pitch makes you get out of the fingers later. If you are having problems hitting the ball on the up swing, then reversing the pitch to the point where the ball is coming off your hand when it is parallel to the lane would benefit you. How much that is is different from person to person, so you will have some trial and error.
It is best to video
tape yourself from the side up at the foul line so you can see the ball come off your hand and land on the lane, and see if the ball goes up after it leaves your hand, or goes straight down to the lane. If the ball goes up slightly before it goes down, try backing off the forward pitch 1/8" at a time until it stops going up after it leaves your fingers.