Oh it's longer than that to heal from the DIEP flap. And honestly, my sister calls hers franken-tits. The amount of slicing they have to do ... ugh. In time the scars do get less but if she's not fat, then she'll have to go the artificial way anyway. I mean I didn't qualify for a DIEP! ME! Because supposedly I only have B cups in my belly. You have to consider that up there, when they scoop everything out, it's actually concave so there's a lot to build up.
Anyway, hoping for the best for your mom. They are growing leaps and bounds with not only diagnosis and options but aftercare as well. We have cancer care hospitals that treat you soup to nuts with alternative care as well like meditation and acupuncture. I would go that route if it's available to you. She'll need you whether she likes it or not. Just up her pain meds every once in awhile so you can get some quiet time ;o)

Average, for horses with some experience at this level