Amalanchier are a good choice. I got a shrub variety a few years back that should stay at the height you mentioned without needing to be pruned Amelanchier spicata. Other small trees that might be worth considering are Fuji cherry Kojo-no-mai or Euonymus alatus.
Amelanchier is the go-to in this situation. Euonymus alatus is nice as is E. planipes if you want something a bit different. Cercis 'Avondale' is a compact slow grower.
I would put it off of centre though. Probably more towards where the bird bath is in the photo.
"What is hateful to you, do not do to your neighbour".
There are two varieties of Amelanchier which are fastigiate, so narrow and not too tall, A. Obelisk and A. Rainbow Pillar which might be worth considering. Alternatively you could consider a Catalpa and keep it to your preferred size by pollarding it once established and again whenever necessary. The Amelanchier would be more attractive to wildlife though.
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I would put it off of centre though. Probably more towards where the bird bath is in the photo.