It's almost exactly 20 years since my wife was diagnosed with MS. Since then she's had three children without any difficulty, and now goes to the gym three times a week. She does have a distinct lack of strength and control on her right side, and a lack of stamina, but most people don't realise she has MS until she tells them.
That said, she's one of the luckier ones, but MS strikes people in a range of way, and I think it is impossible to give an individual an accurate prognosis.
The very best of luck with everything,
AA