What procedure could rectify this dorsal convexity?

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.