I'm so sorry to hear your Molly has SM. That's really good that her symptoms are so mild. Rory has severe SM and malformation, but mild symptoms as well and was diagnosed at 20 months, too. This, combined with the rapid progression, made him an excellent canidate for surgery. I had it done in Tacoma, WA by Dr. Harrington - who is excellent. I've heard good things about Dr. Dewey at LIVS, too. I'd recommend talking to as many neurologists as you can and going to whoever you feel most confident with if you do decide to pursue surgery. I spoke with more than 5 neurologists before deciding to pursue surgery for Rory.
If you have any questions, please do not hesitate to contact me. I'd be happy to talk with you more about why I decided to pursue surgery, etc. Everyone has different opinions and decisions about SM and treatment is a very personal choice.
Hugs to you and your Molly!!
Dogs are not our whole life, but they make our lives whole.