Firstly, I do understand you passion. I've had a very serious back injury myself, and I won't go into details now, but I make it clear that I tought my "lifting career" was over, and that I could never squat heavy again. But after about 1 year after the injury happened I could squat again. In the meanwhile I tried to do whatever I could, but for the first 3 months I did absolutely nothing and got into a state of total depression, basically stopped caring about anything, and I could feel how my body deterioated.
I did not have the money for fancy treatment. So I basically just started training, walking uphill a lot, taxing my body without doing the heaviest movements. I also started doing front squats first, as I found these easier on my lower back. It was the lower back that went south for me too.
Another decision I made was to stop using a belt, and I have never looked back. Never felt stronger in my back. I kept fighting, and then finally about 3 years after the accident happened I had not only gotten back to my previous levels, but also reached an all time best squat of 250kg raw and natural (of course, that's the only way people).
So if nothing else, I never gave up, and I regained my strength and improved even more. But it was not easy.
I am no MD, so I do not know how serious your injury is, but be assured that doctors do not always know what is right, they do make mistakes sometimes.
I had a doctor tell me once to NEVER lift anything heavy on my back, and never extend my arms over my head with a heavy barbell. I never listened to that advice, and that decision have never been better for me. That doctor to did not look like he ever lifted a weight. This doc was unrelated to my back injury, but was even earlier in my "lifting career".
So I'd say to follow your heart, be patient, and build everything up slowly. If you do it too fast, then re-injury might happen. That happend to me a couple of times, and I tell you it is not funny at all.
Good wishes for your recovery and continued ability to lift heavy!