Don’t do that, achrida. You have enough problems.
Your situation takes me back to my (short!) spell in ‘watch and wait’ limbo. I was happy (well, I say happy…) to go away and get on with my life despite having as clear a personal view as you about the way the wind was blowing. I had had no previous neuro symptoms (and the ones I had presented with were going or had gone), there was no family history, DMDs had barely been invented and so were not a consideration and I was far too busy at work to mess about with chasing a life-changing dx. I reckoned that MS would find me if it wanted me, as it did a short time later.
Why do I feel a little bit differently now? (About your situation, that is, not mine.) DMDs. Your neurologist has actually been very frank about your chances; there are plenty would have been more mealy-mouthed about it. Hurrah for frankness: we all need to know where we stand. But to estimate that sort of conversion risk, having looked at you and your scan evidence and your family history and then refuse to engage in the matter of whether pre-dx DMDs were called for seems, well, unhelpful. If he/she had the discussion with you and set out the case for not prescribing them at this stage for x, y and z reasons, well that would maybe be another matter. But refusing to engage with that option as a possibility would leave me feeling dissatisfied too.
If the early-DMD issue is one that you feel strongly about, then get it back on the table. Sue has made some good suggestions about how to go about it. To that I would add that the early DMD exchange might, in the neurologist’s mind, be a quick in-passing exchange that he/she closed off without even thinking about it and has forgotten already; he/she might not know that it remains a big deal for you and demands a considered response, taking proper account of your situation and current professional best practice. Gather your evidence of good practice as well as explaining your views and get it on the neurologist’s agenda as something that needs proper discussion. Your GP will, if you are lucky, be an important ally as you plan how to make that discussion happen. It may be you need a second opinion, now or later (if your neurologist and you cannot come to terms). Again, the GP can be worth his/her weight in gold.