I think your patch is too thick and a bit young. I do walk through one patch that has young trees like yours that are only about 15' tall, the patch is 30' in diameter, the trees are spaced about 5' apart and easy to walk through, they also get plenty of sun.
I was surprised to find about 20 paw paws on the ground in the patch last year, this year I only found one.
We have a native plant garden on one end of the trail I walk, they planted two or three paw paw trees in the garden with name tags to identify them. One tree started bearing a few fruit when it reached 10' tall, it only dropped one paw paw this year because of a late frost. The other trees are about the same size and has never had any fruit.
I walk another trail that has a number of very mature tree 35-40 ft tall, they are on the top of a ridge and get enough sun. 5 years ago the big trees dropped at least 100 paw paws and almost none since. This year a small tree on the side of the trail dropped about a dozen paw paws but the big trees had none.
I can't figure out the paw paw mystery either it, has alway been boom or bust on fruit production.