A few suggestions of trees that grow to around 2- 3 metres and are well-behaved and easy to maintain at a manageable height…
Dwarf Ornamental flowering cherry trees:
Prunus Incisa 'Kojo-no-mai' (Dwarf Fuji Cherry);
Prunus Little Pink Perfection;
Dwarf Crab apple trees:
Malus Admiration;
Malus Sargentii
Malus Aros
Dwarf Rowan trees:
Sorbus Vilmorinii
Sorbus Red Robin
Other trees
Magnolia Susan
Chinese Redbud Avondale (Cercis Chinensis Avondale)
Irish Golden Yew - (Taxus baccata Fastigiata Aurea) - It will grow tall if left unpruned eventually, but it's very slow growing (about 20 years to reach 4 metres height), it has a narrow column habit and very easy to trim to size. Red berries in winter and a golden glow of new foliage in spring.
The shrimp-leaved Sycamore - Acer pseudoplatanus 'Brilliantissimum'. A top-grafted tree (which restricts the trunk height); slow-growing; salmon pink leaves emerging in spring turning to lime green in summer, and yellow in autumn. (It's not a Japanese Acer and it's very easy to grow).
Check the growing conditions for each tree to see if it might suit your garden. Crab apples are usually very resilient trees with year round interest.