Very prominent bony nasal bridge after septoplasty and turbinate reduction. not noticeable before. why?

Could be scar: I would ask your surgeon it may represent scar formation or just swelling that will resolve. If it is scar tissue pressure or an injection may help i would seek the advice of your surgeon.

Septoplasty: Septoplasty should not cause you to develop a dorsal bony bump. Talk to your surgeon.

Saddle nose?: One possible complication of septoplasty is saddling of the nose because of loss of septal support. This may make the bony dorsum seem more prominent. Have your nose evaluated by a board certified facial plastic surgeon.