My daughter has a diaper H as well.
My daughter is now 10months and is still on propranolol. She has a quarter size above her buttocks and some on the sides. The one that worries me most and causes pain is the one in btwn the cheeks. It gets ulcerated right above her anus. That one healed but recently another spot ulcerated. We're using regranex for the ulcerations and it's helping a lot but very slowly. I haven't found much information about laser improving Hemangioma's in the diaper area. Please keep us updated about your child's H.