Where are you located? CA?
When I say it’s a dwarf rootstock, it still grows up to 8-12 ft, per UC Davis. This rootstock produce fruit quite early ( in2-3 years). From what I’ve read, in the east coast, peaches on citation have runted out. Some apricots on citation just died.
DWN grows fruit trees for a living. I don’t know if you should compare your trees to their trees. As you know, quality of soil and other factors such as water, sun, a planting location play a role in how well a tree can grow.
If you want to push your young trees’s growth with fertilizer high in nitrogen, please feel free to do so. You can consider it as your experimental project. Best of luck.