Love to hear from others with muscular dystrophy. What can I expect?

Diagnosed this winter with adult onset Muscular dystrophy - and had RA for 30 years. Had lots of testing DNA etc - single dominate gene! Walking Deteriorating - what can I expect- no one will tell me anything! Do PT twice week and try to walker walk 1:3 mile 2-3 times a week etc.
getting discouraged ( 78 yr)