Things I can recommend from personal experience (my 2 cents anyway):
I think it’s always best to have the motto “hope for the best, plan for the worst” (it’s worked for me).
Re: Kids, if you’re set on having them and want to enjoy your time with them it’s better to have them earlier in case things late a turn for the worst later. I had kids about the same age as you with that fear in mind and I’m glad I did as I deteriorated a lot in their childhood. If I had not had them when I did I doubt I would have had them out of fear, having them was the best thing I ever have done.
Re: finances, again was in the same boat as you as the main provider, do you have insurance for critical illness or income protection (typically 2/3 of your salary until retirement if you become unable to work) already and are covered? If so you have that (find out th correct procedures and conditions to claim so you are prepared if the time comes), if not then there is a way still to get covered for income protection even though your MS is now an existing condition.
Companies frequently have group income protection insurance as a core benefit, the nice thing about this is that as the insurance company is insuring a group of people they can’t exclude someone’s existing conditions. The reason is they’d be excluding someone because of a disability, therefore its disability discrimination and illegal. So first thing I’d do is check does your employer have such a policy in place? If not can you encourage them to take one out as an employee benefit? If not, I’d think long and hard about your career, it may be safer to find a company that has one that you could work for and trying to get a job there (don’t have to but bear it in mind).
Income protection insurance is extremely valuable to have as a financial safety net, it will save you worrying all the time about what may happen to your dependents if the worst happens to you.
This may all be overkill and you may never need it, but it will give peace of mind when worrying about the future. Unfortunately the worst happened to me and I was so glad I worried about this stuff now that I can’t work.