Your waist got bigger bc your pelvic floor and diaphragm got weaker .I've been on it for 12 years straight. Usually 2iu while cruising and 5-6iu while blasting. I don't think the GH has caused a waist size increase but I do feel as you age and keep training hard that your waist will thicken and your hips will broaden. I don't have a 31-32 inch waist when I cut anymore but after 33 years of training I'd say it's 33 or 34 when I'm sub 8% so not a huge increase.
As mentioned, I think pushing high amounts of food with the bloat for months on end, year after year causes more damage to the waistline than GH ever will.