Why do you trim it? We don’t know where you are located but isn’t that just before it blossoms? Also are you certain about the id. Is it definitely a named sour cherry cultivar? The fruit sound more like a wild cherry, maybe from a rootstock. .

Many fruit trees that are self-pollinating like yours will fruit more heavily if more than one tree is planted.

Thanks. I'm located in southern New York State. The tree is called a Surefire Cherry. It's on a dwarf rootstock. This is actually the exact tree I have: https://raintreenursery.com/products/surefire-pie-cherry-dwarf

It is a late flowering tree, which supposedly helps it survive frost damage.

I was always told that trimming the tree encourages more and healthier growth. I don't really go heavy on it - mostly trim some of the inner-facing branches to keep the center more open. I also even out the top a bit.

This is what it looks like right now.

Here are some pics from last Spring. I always get so excited that so many flowers come..but by the time the are "ripe", I maybe get to enjoy one or two cherries out of all of these!

Tart cherries are said to be self fruitful, including the description in the link you posted, although a recommended pollinator tree is also listed. So, you could be patient if it’s a younger tree and it may improve, or add a second tree (yay! more fruit!). Cherry trees don’t need pruning except to shape a wayward branch or remove dead wood.

? Is the tree getting enough water when the fruit is forming and getting up to size?

You might need to fertilize during fruit-set... or just before.

Do you have active pollinators when the tree is in bloom?

Is that a vertical crack at the base of the trunk? And is the root flare buried? It might be aborting fruit if it's unhealthy.

You'll get a lot more flowers if you stop cutting back all the outside branches.

I was always told that trimming the tree encourages more and healthier growth

Since trimming = reduction where is the logic here? Does a body want more tree or less? Because trees that are cut back are then smaller afterward than if they weren't cut back. Even if long vigorous shoots come out from below the cut stem ends (creating the impression of invigoration). This phenomenon (smaller now = smaller later) was demonstrated experimentally decades ago, using test plots of all the same kinds and sizes of trees with one half of the group being cut back and the other not. Then digging and weighing each set later, at which point it was seen that the unpruned group had produced more additional mass in the interim than the pruned.

'The only maintenance I really do is to trim the tree each Feb and March.'

Flower buds develop in late winter to early spring. Pruning at this time is essentially removing a good portion of them.

I was always told that trimming the tree encourages more and healthier growth.

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im going to start counting.. this is the second in a few days.. where peeps want to give a tree haircuts to make it grow more .. crikey ...

if you want fruit production.. learn exactly how to trim for fruit production ... is does not involve trimming all the tips to make it a pretty lawn tree .. and it has very specific timing requirements ...

next.. your lawn is heavily fertd and weed free ..

your tree doesnt need the high nitro lawn fert.. and it surely doesnt need more fert for a tree .. just stop giving the tree extra ...

i also wonder if any bug juice is sprayed on the lawn during the important flowering time???

ken