I guess I just need all the reassurance I can get...

I am 39, f. I hurt my back 15 years ago lifting a box and twisting. I went to the Dr., and they found nothing wrong. The pain gradually went away, but would reappear after heavy lifting. I reinjured it 2-3 years ago, don't know how. I had an mri at that time, and in march '06, the most pain occuring during the past 9 months. The mri results stated: "two-level disc dessication at l5-s1, somewhat more prominent appearing right s1 nerve root compared to the left, desiccated disc at l4-5 with broad-based central right paracentral protruding disc of 3mm with an annular tear and high intensity signal zone, mild fluid in the facets bilaterally at l4-5 and l5-s1." my first doctor was an ortho., and didn't help me, but after I begged, he prescribed pt. The pt guy referred me to a back specialist. Pain occurs after heavy activity, coughing, sneezing, sex, getting into car, putting on shoes, picking something off floor, turning in bed, etc. It is hard to do laundry or lift anything. On good days, I can stand upright and walk ok, on bad, I hobble. Btw, I do not have leg pain, only in my buttock mildly. My current doctor determined that I do not have nerve pain, it is mechanical pain. It feels as though bones are compressing and grinding in my back, and I have much spasming. The l4-5 disc looks thin and is gray on the mri, and the l5-s1 is black. (the healty ones are white.) my Dr. Suggested fusion for the lower disc, and nothing at this time for the upper. Btw, I used to work out 6 days a week, am normal weight, thin and muscular, very active, but now I cannot run or do aerobics or rollerblade, and only work out 2 days per week, very mellow. I will not take pills, it is not for me. The most pain/stiffness occurs with movement, and I want to restore my mobility. Pt didn't do much, am already very strong. I am hoping that surgery can help me. Does it sound like a reasonable solution, or should I wait until it gets far worse?