My thought is, a lot depends on your age and how long you carried the extra weight at your waist. The younger you are, and the shorter of a time you had the extra weight, the more likely your skin is to find a way to regain its earlier form at least a bit. For a while skin that has been stretched looks like a deflated balloon, kind of puckery. (When a woman has been pregnant and her stomach looks like that after she delivers, doctors call it "baby skin.") But if you have youth and activity on your side, I think the skin can remember its past form and tone up at least a bit, with time. On the other hand, if you're past 40 or 50, this might just be wishful thinking. Do some exercising of your core and a lot of stretching, and see where you get, is all I can suggest. I hope it isn't hanging like an empty wallet. And I'm sorry it is putting a cramp on your intimacy.
Unfortunately, it's pretty common to have "extra skin" when losing a good amount of weight in a short period. If you went from a 12 to 7 in 3-4 months, the weight came off pretty quickly. Once the skin has been stretched (as in weight gain), it tends to lose elasticity so it doesn't "bounce" back into shape when the underlying fat is gone. The older we get the less elasticity in our skin. You can try certain exercises to build the stomach muscles, which may help "fill" the skin, but there's no guarantee they will work. The most effective way to eliminate the skin would be surgery, but most of us can't afford that and since you don't want it anyway, there aren't a lot of options.