Firstly these comments are not helpful at all to you.
I'm so sorry that this has happened to you and I sympathise with you and I know exactly what you mean with the lack of support.
My situation is somewhat similar to yours.
I had my DS in August last year he is approaching five months.
At first breastfeeding was painful and he looked extremely uncomfortable when feeding, arching his back etc.
I saw a breastfeeding support worker who was absolutely useless she just kept saying you're doing well and I don't see the issue you are facing.
Then I went to a breastfeeding work shop and saw a breastfeeding specialist who then told me my DS had a posterior tongue tie.
NHS waiting times was eights weeks, we were so desperate as breastfeeding was becoming unbearable for both of us. We paid privately to have his tongue snipped. The midwife who came to perform the snip explained to us that she rates the tongues performance after a few checks, 0 to 10 zero being the lowest she rated my DS at a two. She said that the skin was so thick the likelihood of it growling back was very high.
After the snip breastfeeding became less painful for me but my DS was still having issues. He would sound and look as though he was in pain when feeding and wouldn't relax always flipping his head back, latching on and off, crying, arching his back I mean it was awful for us both.
So we paid privately to see and osteopath, she said my sons jaw was stiff and that he had acid reflux. He had six sessions which to be honest I don't think it helped very much at all.
Back and forth to the GP and HV eventually my DS was prescribed baby Gaviscon. In time my DS had then what the HV called food avoidance, he had basically linked pain with breastfeeding and was shallow latching. This then affected my milk flow.
Now four month later after all of those challenges plus a very bad chest infection my milk flow is so low that I'm only expressing 2oz - not that long ago I was expressing 8oz.
The guilt from my failure has made me feel so sad about this. I'm still trying after three weeks to get my milk back up but we are taking about a lot of expressing, like every hours. Plus now my DS has got so used to the bottles that he doesn't suck hard enough to send the signals to my brain. A sad situation but I'm learning to just not expect anything and I still do breastfeed him for comfort even though he's now on the bottles.