Oh OP, massive sympathies from me, I've been through the exact same thing.
I had my first attack when I was 8 months pregant, I actually only had one attack while pregnant, however when I had my baby (now 4 months) the attacks became much more frequent and I ended up at the OOH, walk in centre, GP, A&E etc as nobody was telling me what it was. I knew it was gallstones from my own research but professionals were telling me it was acid reflux, gastroenteritis, gastritis etc despite me describing the levels of intense pain.
I ended up hospitalised when my baby was 3 months old due to getting a stone stuck and having pancreatitis and jaundice, a week later I had an operation to have my gallbladder removed. When I was in hospital there was also a lady who was pregnant, pregnancy can cause gallstones unfortunately.
Honestly, nothing helped the pain for me, in the end I was on zapain, antisickness tablets, buscopan, omeprazole and naproxen and it didn't help. I also read that drinking apple cider vinegar helps so I was doing that daily (absolutely vile stuff) I was also having peppermint tea and taking daily magnesium capsules, again, it didn't help.
The general advice is to follow a low fat diet, I ate things like salad, tuna, sweet potato, olives, wholemeal bread, pasta and rice, salmon, other fish. There's also a gallstone support group on FB where people share food ideas etc.
Can your name be put down for surgery now? I would ask for it to be put down and then once you've given birth ring the surgeons PA and beg for an early appointment, a cancellation slot etc.
If you experience a blocked duct you need to go to A&E immediately, signs are pale stools, dark urine, yellowing of the skin/eyes, abdominal pain that doesn't go away, sickness, high temperature etc. When I had pancreatitis and jaundice I presented at A&E and was in a bed with a drip within 2 hours so they do take it very seriously.
Please let me know if you have any further questions, I am not yet even 2 weeks post op so it's all very fresh. The operation was fine, no issues at all. The good news is you will absolutely smash labour, as to me, the pains were very similar intensity wise, during an attack I often thought I'd rather give birth, and I did that with no pain relief at all, which highlights how horrendous the attacks are.
I'm so sorry you're going through this, it really ruined my life and newborn experience for a while, I was terrified and anxious of an attack, wasn't eating etc. Please, please make yourself a nuisance once you've given birth and make sure you're operated on ASAP. Good luck x