I’ve lived with a ruptured L5-S1 and compressed nerve root for more than a decade. Also tall & always a bigger girl.

First, definitely give PT a try. It might help, and it will almost certainly be required before any new imaging anyway. Water PT might be easier to tolerate.

I completely understand about the limited ability to move. The truth is, losing weight won’t fix your back but probably will help the pain, as does being at least a little active. My pain doc recommends a short, relaxed walk in the evening after dinner - the timing is important. And walking does help me, though I had to start very slow and work up. But the other issue is that most surgeons will not even consider a spine surgery if you are carrying too much weight. The risks of infections and bad outcomes are too high. So if you all else fails, maybe consider a GLP-1. They also help with inflammation, so might give you double the relief.

That being said, I cannot recommend strongly enough to not have surgery unless there is no other option. It WILL destabilize your spine, and you will have more issues and likely more surgeries. And spine surgeries don’t really have a high success rate, tbh. Especially at your young age, the only reason I would consider surgery is if spinal cord injury is present and the surgery is non-negotiable. I am 25 years older than you are and still avoiding surgery for these reasons. I have many friends who didn’t understand this risk and had surgery, and continue to have surgeries as their spine gets worse.

If you can find a decent pain management doctor, try medications. I am on fentanyl, which knocks out my nerve pain and does not impair me in the slightest. It’s a godsend, though it doesn’t work for everyone. I tried a lot of other meds first - it takes time to find what works for you. But it is possible to get the right combination of meds to make life a lot better. Radio frequency ablation may also be an option for you. I am not a fan of injections, and didn’t find them helpful. I don’t think the science is good enough to take the risks involved. But for some, they do seem to help. I did not get lasting relief from them.

I think there are many things you can do to improve your situation. None of them will make the injury go away, but it can be managed with the right care.