Hi, just to let you know a similar thing happened to me and I managed to get back to exclusive BF (although I now give one bottle of formula at night, so DH can give DS one of his many night feeds!)
however, I hadn't got to exclusive FF, just top-ups. Also I started topping up at 2 weeks, and then tried to stop topping up at 3 weeks!!
But I can tell you what I did, in case that helps.
I spent a couple of mornings and afternoons in bed skin-to-skin with DS, feeding almost constantly. (You really need an understanding DP for this, so you can just stay in bed for half a day at a time!!)
I took fenugreek.
I always offered the breast when he cried for a feed, before topping up with formula if necessary (and cutting this down VERY slowly!!)
I'm not saying that's necessarily the correct thing to do. I don't know! It just worked for me.
But it was really hard at times. In the middle of the night, when DS wasn't latching on well, when I was in pain, and when it all just seemed too difficult, I would've given up without the support of my DH.
Also, it took a good month to get to the stage where it wasn't tough any more.
HOWEVER, now, apart from the one bottle at night, he is feeding well, and I absolutely love it! Really do!! He's now nearly 17 weeks old, and I am so glad I fought for this.
Am so angry now at being told to top-up (he was also low on the weight chart. I just didn't know enough to argue with the midwife). I really don't have any opinions against FF necessarily. It's everyone's own choice. But I have to say, I'm so glad I am now BF.
Good luck!!