Fruit trees need several years to develop a sturdy root system to provide future years of abundant harvests.

Your trees grew 8 inches. That means they're working on it.

GIve them another year. (Well, you may want to move them when they're dormant this year. They appear to be way to close to the fence unless you're planning on an espalier. Even then, the fence will restrict air movement which is critical for limiting leaf & fruit diseases.)

The soil looks disturbed, weedy and cultivated. If it's cultivated, you might be damaging some of the new roots.

I don't see any of the suckers you mentioned. Make certain you continue to remove them. Snap them off as soon as possible. If they remain, they will direct the assets to the suckers, not the tree.

Well, to be clear, they grew 8 inches in last year's growing season. This year, one of them literally grew zero inches, and the other one grew zero inches on every existing branch and popped out one new branch (of about 8"). They've produced a lot of leaves, but as you can see in some of the pictures, at the tip of the branches where there normally would be new stem growth, the leaves are all just piling up in the same spot. I guess my worry is that there is some hormonal growth suppression going on, for reasons that I'm not aware of.

(Yes, I've been removing the suckers, and these are intended to be espalliered.)

It takes at least 2 seasons to settle in.

@Jason, very interesting; my Gala also didn't break any buds until July this year. Maybe it is related to warm winter. Hopefully we'll get more chill this winter.

Feed it 30grams MAP fertilizer in the spring

@Benjamin, thanks for the tip ... I'm not familiar with MAP fertilizer; could you describe what it is and how it would help in this situation? Thanks!

It's a 'Tree Starter' fertilizer used by commercial horticulture operations where I work, we use it in the first year or two to develop canopy.

This is the product we use;

http://www.jfcmonro.co.uk/mono-ammonium-phosphate---krista-map~675

I don't know where to get it near you, or anymore than that sorry.

In USA called DAP its common called popup fertilizer 18-46-0 18 nitrogen and 46 phosphorus 0 no potash. It does work make plant take off while young. Using 18-46-0 application back heels up to trunk and spread outward. The 46 is quick release phosphorus.