|I didn't have this exact problem, although on my younger son (very skinnny), the OS was definitely a bit drooper than on my older son (chunk). That being said, with the AF on, it didn't really matter, as that kept everything in. You's be surprised that you don't really need the snuggest fit to do the trick. I was looking at the OS last night and wondered if it would be possible for you to make the waist smaller on the front-up setting. If with the diaper not folded over, having the wings meet in the middle is still too small for his waist, have you tried using that center snap? With the diaper facing you, if you snap the left wing into the second and third snap from the left side and then snap the right wing into the center snap from the left wing and the third snap from the right, you can have a pretty small waist. I'm not sure if that would make the thighs too tight then, but thought it might be worth an experiment?