Ok a bit of an update...

Dd is still BF'ing much to my surprise. Sunday at work I managed to express even though I was actually working at an exhibition in the city. Thankfully the exhibition organisers allowed me to use their office to express. It was a bit of a weird situation but at least I managed to get through the day.
I have tried the "switch back" idea the last two days and surprisingly Dd has gone with it which she hasn't when I've tried it in the past. I have also had her feed to sleep twice in the last 4 days which she hasn't done in a very long time. When I've done the switch back and she fusses I've actually squeezed and squirted her in the face which is usually during the second time on the side.. I've also had a bit of leakage with letdown on the opposite side so I'm taking this as all good things.
I know I'll never make enough for a full feed but happy I'm still plodding along.
I'm going to monitor her formula feeds for the next week to gauge how much formula she is taking as I stopped noting this down when she was about 6 weeks old.