I think righty reckons you're feeding twins!
Ok, so some green poos, etc, might suggest lactose overload. particularly if you've got an oversupply on one side. Sounds like you're already doing the right things - I hope it settles down for you.
Maybe try expressing a tiny amount before the feed, rather than a large amount? Or was the 100ml a one-off? As Jen says, that will encourage more production.