I am so so sorry for the pain you are having! I think what helps the most is a good PT or chiropractor. I would switch till you find the right fit. Also, exercise and walking. When I sat or at night my pain was the worst. I also got relief from a good massage therapist. I've also heard that acupuncture is a good alternative. I have heard from other that for most people the pain goes away as soon as you have the baby. It was not the case for me because my disks.
During my first pregnancy I had low back and sciatic pain. It was the worst pain I had ever been in. After the birth it became even worse from an episode of lifting the infant car seat carrier. During the pregnancy I was going to PT with not great results along with massage which brought relief. After the birth I tried to get my primary care to send me to a specialist when the PT was not working for me, and he continued to recommend the same PT. I don't think that therapist worked for my situation. Thankfully, for PPO's I went above him and contacted a specialist myself. I was limping at this point. I think I had a PT that just wasn't working for me too.
I saw a Physiatrist at a spine center (we lived out of state at the time). I had an MRI done, had two herniated disks L4-5, one severely herniated, and during six months had two cortisone injections and physical therapy.
I still get flair ups, but with exercise and proper body mechanics I keep on top of it. I had started doing pilates with a trainer which has been great for my back as I am also pregnant with number two and due in March. My first is 20 months.
I'm not sure the age of your babes, but I was still able to breast feed during the cortisone injections. I had to pump and dump for 24 hours, and my husband did all the feedings with a bottle. It didn't change my supply as I BF till 18 months.
I hope this helps, and keep in mind that the whole process takes time to see results. I really feel for you! Let me know if you have any other ?
K.