DH and I have lived off of 250 a week. Granted, this was pre DD, but we had two phones, a computer for uni work but no TV, we paid bills, rent, food, public transport costs all factored into that. It was hard. There was literally no wiggle room, picking up a chocolate bar at the supermarket would throw out our budget, and we would eat rice and veggies most nights. I'm not suggesting you go this extreme at all, but it does illustrate that you can always cut back more. It will be hard, but I don't think you have another option. Without sounding harsh, it sounds like you have lived well beyond your means for a long time, so I really think you need to cut right back.

ETA During this time, I babysat for cash. Maybe oh could look into that? DP could have your DD in the evening, and you could babysit in your local area. It's a great way to make some extra money.