Hi OP, you need a more supportive GP. Or you need them to refer you to someone who understands about pain medication and pregnancy. This could be as simple as a specialist midwife, doesn’t need to be a pain clinic.
I’m 22 weeks pregnant at the moment and had to come off the medication that I took everyday to keep the pain at a lowered level, the equivalent to your pre-gabalin but I could still take paracetamol and codeine when TTC.
Now I’m pregnant I can also still take codeine and paracetamol. I don’t take them every day, and I can count on 1 hand the number of times I’ve taken codeine as I try to follow the idea of taking the lowest dose for the shortest amount of time. But it’s there if I really really need it.
I’m often quite hard on myself and just try and put up with it, my midwife has actually told me I should take more painkillers if I need them. Me being stressed out and upset isn’t good for the bean.
I had to slowly wean off the other medication and then have it out of my system for atleast 3 months before TTC. If I’m honest it wasn’t as bad as I expected it to be, it just meant that when the pain really flared up it was REALLY bad but my to day pain levels weren’t that different.
I generally manage using heat, TENs and trying to listen to my body a bit more. My work are also more understanding now too. If I physically can’t sit at my desk for a few hours they understand that I can’t just drug myself up and crack on. WFH has also helped massively - I never have to carry anything 
A big part of what helped me was acceptance. I’m in pain all the time and that’s okay. I stopped treating like a fight against my body. I don’t do things that hurt more but ‘might’ fix it in the long run.
Also don’t believe all the people who say you’ll be on less pain because of pregnancy hormones. That hasn’t been the case for me. But being pregnant has helped me like my body a lot more, my body is actually making something and is doing a good job! For a change 