3 months post op buccal fat removal, have hard lumps at the incision site. Why's it taking so long to heal up?

I got my buccal fat done on january 12th and still to this date there are still hard lumps on the incision site to the right. It's not massively painful but when i press on it, it's just obvious it hasn't healed yet like a very minor pain you get when a wound is healing. Why's it taking so long to heal up? My other side there is still the lump at the incision but I can still tell a difference from before whereas right side it's just not healing up to well