Did you change your nose?
I suppose it might be possible to change the bony profile and/or compress the nasal septum in the lower 1/3 of the nose enough with constant pressure in someone who is still growing, but even that is very unlikely. There are many reasons you could have difficulty breathing. You need a careful evaluation of your nasal airway. Also, the surgeon will need photos of your nose from when you started pushing to compare to present day.
Unlikely to have caused damage to nose with pressing
It is unlikely that you caused permanent changes in your nose or septum by pressing on it. It takes a fair amount of force to cause this type of change. You can have an Otolaryngologist evaluate your septum and your breathing concerns.