I am right there with you. I have been block feeding for a few days now. I am going for about 5-6 hours on each side. The side I am not nursing on gets very full and leaks quite a bit, but that should resolve itself at some point.
I was also pumping for DH and have stopped doing that until we can determine what is going on. DH used a frozen bottle of milk last night and noticed DS2 was fussy right after--it was a bottle expressed prior to beginning this process and was likely mostly foremilk.
Did your DD choke and gag a lot before you began block feeding? That was a big clue for us. DS2 has also gained a lot very quickly...yet another clue to my oversupply.
We are still experiencing fussiness and gas here, but it does seem to be a bit lessened. It has only been a few days, though.
Good luck to you and your LO,a nd keep us posted!