Paw paw flowers are both male and female, but they can't pollinate themselves. They need another paw paw to pollinate them. Most groves are from the same root system, so even though they have multiple trees, they are essentially the same tree. Hence, pollination will not occur. If the different groves you have are a long distance apart, that could be a lot of your problem.
Lots of folks have problems with paw paw pollination, but if you can get different trees close to each other, that will help. I have that same problem at one place where only one grove exists. However, at another place where I planted seedlings from different groves close to each other, I get good pollination.
Insects are not attracted to paw paw flowers like they are apples and pears. That's one reason why pollination seems to be an issue for a lot of folks. I've even read about people rubbing bacon grease on flowers and also taking a paint brush and moving pollen from one tree to another. Of course, your idea of providing more sunlight will probably help too. Even though they are capable of fruiting with less light than apples, more does generally help.
