How can I help flatten out and lighten skin graft on my nose?

However I an tell you that 5 months is very very short time for the maturation of a skin graft, give it not less than 1 year to assess options to correct the patch effect.

You are doing all that you can for now, and the graft is still in the maturation process 5 months later. You may want to talk to your surgeon about procedures such as dermabrasion and laser resurfacing a few months down the road to further refine the result and get better camouflage of the graft.

Throw away the silicone sheeting. It's useless. Use a good sun  lock and makeup. Time may also help.