I can't say that I've ever heard of the spinal cord being too long before, but I have heard of the connective tissue disease. Here's one of many reference links:
Undifferentiated Connective Tissue Disease - In-Depth Overview - HSS.edu - HSS
Have you had thorough blood tests by any chance? If so, are there any abnormalities? If you have not had thorough blood labs, you might consider Klongen Labs, Fry Labs et al.
Whatever the case, more conservative spine docs would possibly exclude you from disc replacement surgery, since this disease is generally considered to be an autoimmune disease.
Where is your PCP in your journey? Is he/she guiding you?