We have a 100 year old (probably older) apple tree in the back yard. It’s easily 30 feet tall and it’s beautifully gnarled and provides shade for us all summer long. It’s beautiful and an absolute menace. Our tree and its sidekick tree in the driveway drop literal tons of apples on us all.summer.long. It sounds like constant warfare as the apples drop onto the metal roof of the woodshed, shop, and MIL house. They start to fall off when the apples are tiny, grape size, and it continues until the last one falls in October. The neighbor deer likely kept them cleaned up before we bought the place and fenced in the yard because there wasn’t an apple on this whole place when I first saw it in the spring. So now the deer hang out in the alley catching the bounty that is funneled to their side by the slant of the roofs. We use a manure fork and easily fill three or more big rubbermaid carts with apples on a weekly basis, one cart a day when the apples are bigger. We park the cart in the alley and the deer clean those up too. 
I can hear them fall now as I type. If we don’t pick them up daily they rot in place, attract bees and flies and act like ball bearings to walk on or dog poo to squish on. The cats and dogs are constantly getting hit by falling apples. They look like GRAPES on the tree. Early in the spring we knock off as many blooms and baby apples as we can reach and still they fall. They land all over the cars and the windshield trenches of the rigs parked in back are filled with apples. When I drive away the Expedition and stop for the first stop sign apples roll off the roof rack and spill all over the street. We keep our pontoon boats back there and the last time we floated the river we were escorted downstream by apples bobbing along with us as they fell out of the nooks and crannies of the boats. By the end of the summer the only apples fit to use are 30 feet high and out of our reach. I’ve scavenged a few that were usable and they’re great, probably an old Jonagold variety. But I practically have to catch them as they fall so they aren’t bruised. Which isn’t hard to do since we have all been hit by falling apples and if you want an apple in late summer you just have to stand out there and wait a moment then try to catch it.
Despite all this, we love the freaking tree. It was neglected before I bought this house so was overgrown and tangled. Our new neighbor across the alley is an actual arborist so he helped my husband trim it up this early spring. They were merciless, trying to get us a year where we had shade and no apples, but it only worked on half of the big tree. The sidekick tree and half of the big tree seemed to feel compelled to do their part to make up for the lack of production on the non-flowering half so we gained no respite. I suppose we will tackle it again next year but holy mud. I call this time of year Applegeddon.
I googled a ton about this tree over the last few years that it’s been inflicting apples upon us. Most important to me is that the tree does not die, we love it unconditionally (and we would bake in the summer without it). We were glad when the arborist moved in and encouraged/helped us to cut it waay back but it had been neglected for so long we were only supposed to go 1/3 back, in addition to the shooters. There is a system to it if you want the tree to live. If you don’t care if the tree lives, you can carve it up with a chainsaw and the tree will LOVE it and reward you with perfectly behaved apples.
Our tree had enough large branches and the roof of the buildings were tall enough to be a big help as they cut but without those advantages I would definitely hire it out. There is an art and a significant danger to it.
I’d definitely talk to a pro since in addition to wanting them trimmed correctly there are several possible reasons why your trees aren’t having apples. Don’t fertilize under the trees since it can cause overactive vigor (?something like that), make sure you have pollinators, etc. Google will shed a lot of light for you too. Our tree is a work in progress because it’s not healthy either, it’s appling all wrong.
I would give my left arm if this tree would stop with the apples. It’s famous in the neighborhood for the constant whack…whack…whackwhackwhack!!..whack of apples hitting the metal roof. Thankfully our neighbors have a sense of humor about our situation and the deer love us. A little yearling buck and doe just walked by my window to check out the daily offerings.
You could put this in the “careful what you wish for” file. LOL I was SO excited when I found out this was an apple tree… 
Good luck with your trees!
