It seems to me that you need to find a new neuro. Or perhaps a primary care physician who will not be afraid to diagnose the MS, and get you started on one of the disease-modifying treatments available. 2004 is a pretty long time ago -- I wasn't clear by your post if you've seen a neuro since then?
You say you had two bouts of optic neuritis...did you see an ophthamologist to confirm that, and does your neuro know about that? Sometimes they won't diagnose MS at the first visit, but when the patient calls or comes back in with new symptoms -- like optic neuritis -- then they're ready to move forward.
It might be time to get new MRI's, see if there are more lesions, or lesions in different areas, and then press for specific treatment (Avonex, Betaseron, Rebif, or Copaxone).
As for the bloating and constipation -- are you indeed constipated? This means: are your stools hard, in small balls, painful to pass? Or is it more that your bowels are sluggish -- you don't have daily bowel movements, or even bowel movements every couple of days...but when you do, they are loose; formed, but loose? The sluggish bowels are another possible symptom of MS (although there are other causes, too..but since you had the colonoscopy, most of that has been ruled out, or at least checked for.) You should probably tell your neuro about this, too.
If you are OK with your current neuro, then an appointment is in order. Get the records from the eye doctor about the ON, and talk with the neuro about that and the bowel problems, and maybe he'll take action.
But indeed if you're not confident in him, taking all this to a new neuro, and getting new and current MRI's, might be the best.
...I am not a doctor, nor health professional, and don't pretend to be one, here.....