15 months post-op, what can be done to improve my surgery scars and what could have caused their appearance? (photos)

You are doing all of the right things but I wonder if you are massaging the incision with silicone. I know this might sound a little over simplified but silicone is wonderful and necessary and I would encourage you to use it but it must be massaged into the scars very firmly twice a day and then use the silicone strips or sheeting at night. Massage and silicone are the very best ways to get a good looking scar but the massage must be daily, firm, frequent and done for 12 months at least. I would agree with the laser but I would not stop the silicone massage. It will work but only if done in the manner I described above.

Dear J_2020,
I understand you are concerned with the appearance of your scars. As your scars heal, it should flatten out and lighten. Loss of pigmentation or hyperpigmentation may also be experienced but will resolve over time. Always follow your surgeon's post operative care instructions when it comes to scar management to avoid any complications like infection and for faster healing and recovery.
Daniel Barrett, MDCertified, American Board of Plastic SurgeryMember, American Society of Plastic SurgeryMember, American Society of Aesthetic Plastic Surgery

You appear to be a good candidate for scar revision. Your surgeon will excise the wide scars with the anticipation that the scars will heal more favorably with less tension on them. You can begin scar therapy as soon as you are cleared by your surgeon to do so.