I double bag them too when I am post partum because I am cheap, but I'm sure you could find a really good bra for large breasts.
It was such a shock after my first child to go from these perky little A/B boobs to big hurkin D's--and I never did get my perky little boobs back--they got little again eventually, but rather sack-like and droopy.
Sorry if that's too much information:+
Maggie