Mg 15 symptoms and conditions

I was dianosed with an immune disorder of the inner eye. It was advanced enough that regular treatments were not effective. So the dr. started me at 60 mg of prednisone and started to taper it off at 20 mg. every 2 weeks. At 6 weeks, it was observed that my symptoms had reappeared and so he started back at 60 and the tapering was much, much slower (50 mg, 40 mg 30 mg 25 mg 20 mg 15 mg 10 mg 7.5 mg 5 mg 2.5mg) the first week I had panic attacks and wanted to physically attack people. I couldn't sleep. After that I had mood swings, fuzziness, forgetfulness and confusion, all I wanted to do was lay on the couch. I had heart palpitations, moon face (people thought that I'd had dental surgury) went from a size 6 to a size 12. I had terrible yeast infections, and wanted lots of fluid and had frequent urination. It was horrible. By the time I was done (and I had withdrawel symptoms long after I stopped taking it) I'd lost 2 years to the side effects. I do get to keep my eyesight. Fair trade, I suppose. In the next year and a half I lost weight down to a size 2, not as good as it sounds, all my muscle tone had gone and I'm having to rebuild from being nearly skeletal. The worst part of it is.. at any time I can be put back on prednisone and will probably choose to over losing my sight. At what point does one have to worry about osteoporosis? How much prednisone for how long effects the bones? There are things I'd like to do, but I'm not sure if I should.