Hi, I had horrendous issues with oversupply and overactive letdown when DS was a baby. I found a few tricks helped:
- laid-back feeding... google biological nurturing, they have a great video that shows how. I just lay back in a recliner chair, that was good because I could sit back up again when letdown was over and the flow slowed as DS was pretty picky about how hard he had to work. I also fed lying on grassy hills at mothers group, in the bathtub when it was too hot to feed comfortably, etc.
- massage the breast up near the chest wall (not on the areola) to release some fat from the walls of the ducts before LO starts feeding, helps with the foremilk overload that was giving you green poos if it happens again, also helps ensure LO gets more of the fats before they're full.
- block feeding can help reduce supply to more reasonable level. Your blocks can be long or short - feed from one side for one feed, the other for the next feed (let the one that's full stay full as much as you can comfortably do as that's the feedback mechanism to tell your body not to make as much milk. My blocks got to 12hr - one breast for day, one for night at some stage there.
- Massage... has to be the same direction as the colon moves, so in a rainbow shape basically with the heel of your hand at the bottom of his tummy in the middle. Sweep your fingers from her right to her left. Also push legs up into belly gently to help the gas along.
- find a good way to burp her, especially when your supply is highest. That's at that middle of the night feed and through the morning which is consistent with what you've written. Anything where there's some pressure on her belly helps - on your arm with legs either side of your elbow, hand supporting head; sitting on your lap (only once she can hold up her own head because you have to put on hand on her belly and the other does the massaging); over your shoulder...
- infacol can be good or bad for LOs with gas. It makes bubbles join together so it should make burping more efficient but can make trapped wind pain worse. I found DS did better without it.
I think once you get the wind under control, the sleep will come. You're doing well already, so these little tweaks should give her the relief she needs to sleep better.