What procedure could rectify this dorsal convexity?

From your pictures it does appear that the nasal bones are separated  (open roof deformity) which can be usually corrected by nasal osteotomies to bring the bones together.   Your nose appears wider than ideal which is consistent.   An in person exam would be necessary to confirm.  Usuallybsone cartilage can still be harvested from the septum after septoplasty.   Consult with a surgeon experienced with revisions.

In person exam is essential. Based on limited photos-in the right,experienced  hands- your nose can be improved with Revision Rhinoplasty -preferably performed through a closed technique. I suggest that you seek an experienced Board Certified PS for in person exam

Fanningsa, Only an in office exam can give you a good answer. Seek the opinion of an experienced plastic surgeon that specializes in only faces and averages about 100 rhinoplasties a year. See the video and good luck!

The area that you describe looks to be the area where the bone and cartilage meet on the nasal dorsum (bridge).  While an in-person examination would be necessary, often these irregularities can be smoothed out if still present after two years by rasping or smoothening this surface.  It is not uncommon, but can be corrected.  

 The limited photographs appear to have an open roof deformity, but this must be confirmed at the time of an in-person examination.  The amount of cartilage left over on the inside nose must also be determined prior to surgery. Rasping the " corners" of your nasal bones would be helpful in addition to osteotomies place in the Nasal bones. A small fascia graft  harvested from the scalp may be of some benefit as well.