I tried my hardest to BF with Camperkid, but he wouldn't/couldn't latch on. I ended up having to express etc for a few weeks and then my supply just got up and went. I beat myself up for it for about 5 years or so.
This time, throughout my pregnancy, I formulated a plan for bfing, which was to express a bit of milk to get the nipple into the right shape for the new baby to latch onto as I think that I was engorged last time..... So, when Camperbub turned up, this is what happened:
As soon as she'd been checked etc. she was put to the boob and did try to feed. Over the next day, she turned a nice shade of yellow, was taken to SCBU because she was jaundiced and too tired to feed. She sunbathed for a couple of days and was fed formula through a tube.
When I got her back, she just couldn't take more than about 10 ml at a time. So, I was expressing, trying to bf and giving her formula, just to try to get as much fluid into her as I possibly could. Unfortunately, we had a complete numpty of a midwife who told me that it wasn't good enough that Camperbub was taking it over a four hour period, it had to be taken every four hours - and she worked in new money, which I couldn't understand - Camperbub was 5lb 8oz when she was born, so that equates to 3oz formula in old money - this midwife had this convoluted formula for doing it all metric.
Anyway, I digress. We were kept in hospital for a week and I had to have the consultant come down and say that we could leave - which was because Camperbub was my second baby, so I knew a bit more about what I was doing.
Mixed feeding continued for a couple of weeks just to try to get the weight gain going. But I managed to get more expressing done and so Camperbub moved solely onto breast milk. One night I was just too tired to go downstairs and make a bottle for her (this was about 3am) so I put her to the breast in the hope that she would feed OK and she did, so that's how I managed to get her exclusively bf and we managed it for 10.5 months after all that. HTH