You can still prune but, seems like theyr'e not growing much?
Then..compost, old manure or higher middle number fertilizer.

Same issue with mine in Central Kentucky, but for semi-dwarfs! On the 5th year and am lucky to have 1 or 2 apples. I even do the routine fungicides\ pesticide schedules. Part of the problem for me is that although Fuji and McIntosh are supposed to be compatible, the Fuji blooms first and just as it is closing off its last blooms the McIntosh starts blooming. There is a very narrow time (talking a week at most) where both trees have a few blooms each. I just planted two Goldrush dwarfs that are supposed to be compatible with both, so I am hoping for a super long bloom time created by adding these to help the Fuji and McIntosh. I think pollination is my biggest issue. I'm the only yard around for miles with apple trees evidently! I did put out a liquid blooming and rooting fertilizer a month or so ago, so will see if that helps. The local gardening radio show guy said to fertilize in the fall and in winter wouldn't hurt, so I figured I would give that a try too.

Maybe your issue is also pollination. I don't see many bees around anymore. I am also going to plant a lot more flowers this year to try to attract more pollinators.