Happy New Year, everyone. Yes Wallace, I'm that very same Kiwikat - and I'm astounded you remember me. I hope for good reasons! 
To bring my story up to date - I couldn't get a private appointment for dd any earlier than 6th Jan, which was two weeks away, so decided to go with that. However, things looked worse on Thursday 23 Dec, so I took her back into A&E, and this time saw a surgeon who seemed to know what she was talking about. It helped that she saw for herself what was happening. We went back the next day - Christmas Eve - for a dye enema, which showed nothing, but the senior surgeon also saw it happening for himself, and booked her in for an operation on New Year's Eve. A wait of one week was better than two, and on New Year's Eve she had a stoma, and the surgeon will operate to fix the fistula when she's a couple of months older, and is a bit bigger. We were in hospital for 5 looong days - nights of a comfort-sucking baby, kids in pain screaming/crying so no sleep - they kept us in so long as Monday was a Bank Holiday and the stoma nurses weren't in until Tuesday and they really wanted me to be well-instructed. The good news is that Little G is in fine form, pooing no longer gives her pain, and I am getting used to the whole thing. So glad I pushed for action on this! I talked to mums of other kids who'd had or have stomas and that really helped a lot, but I haven't been in the right headspace to post about it until now.
However, I'm now feeling less sleep-deprived, G is happier, I'm learning to live with the stoma, and would love to get together for a London meet-up if there's one being planned.
Hope you're all doing well, and your babies are happy and bonny.