Belly button — stenosis ? PO 5 1/2 months TT (photos)

It seems that you're very unhappy with your results. To answer your one question, an umbilical or belly button scar can usually be revised for a lot of reasons after a tummy tuck but that is obviously an additional surgery.  I would recommend that you see a board-certified plastic surgeon in your area that is a member of both ASPS & ASAPS and performs a lot of tummy tucks and liposuction. Good luck with your future correction!
I hope my answer helps and if it does, please take a moment to up vote this answer on the “respond” button on the top right.  Have a great day.

It definitely appears that you have developed a hypertrophic scar around your belly button. For whatever reason, this incision in particular seems more prone to hypetrophic scarring. I would attempt 2-3 steroid injections, spaced one month apart. This would be a more effective treatment than a topical steroid cream and would hopefully soften up the scar and shrink it a bit. If you can get the scar to be less hypertrophic, I think it will decrease the overall stenosis. 
Emile N. Brown, MD
Johns Hopkins & Harvard Trained Plastic Surgeon