You are absolutely correct, the only opinion/decision that really matters is your own, since that is the one that you have to live with.
That said, if it were me (and I was there at one point), I would wait on colectomy until you feel it is your #1 best option. Go in with doubts, and you are bound to be second guessing yourself for all eternity. But, I am not sure that there has even been a surgeon recommending this surgery for you.
While I am unsure why you think that medical options are more dangerous than surgery (other than your issues with accutane, which are not the same), sometimes that is the case, sometimes not. Plus, having a colectomy is in no way any guarantee that you will not needs those other drugs in the future. So, unless you are steroid dependent, having serious side effects from your current medications, or showing dysplasia or cancer on your biopsies, I do not see a pressing need. It has been 17 years since my surgery (after nearly 24 years of UC before surgery) and I am on many medications, mostly for my enteropathic arthritis (Simponi, Azulfidine, Vicodin, Robaxin), and unrelated medical issues. These are things that cropped up years after my colectomy.
Aspartame is not similar to Accutane, so I am not sure what your concern is there.
I feel pretty sure that Dr. Varma would not even recommend colectomy unless it was warranted, and it does not seem like you are there yet. But, it would not hurt to have a consult with her to find out what the criteria would be, if only to set your mind at ease in regard to what a good plan would be for your future. Any surgeon who would do this surgery just because you requested it, I probably would run from that office. That is not a good standard of practice.
The j-pouch is a great option for those who actually need a total proctocolectomy, but not a completely elective procedure. I probably held out too long, but if I had opted for surgery at your stage, I would have had an end ileostomy, because the j-pouch was not a common practice at that time. Something really great may come along for you. Lots of new research in the pipeline...
Jan