Help for a new rider

I have just recently decided to learn to wakeboard. I have a very minor case of cerebral palsey in my left arm and leg. I am having a little difficulty getting up. I was hoping someone might have a tip to help me compensate for my physical limitations. I seem to be plowing behind the boat and when I feel as though I am starting to rise out of the water... I lose my grip on the rope. I don't know if this is a problem attributable to a weaker grip with my left hand or if it a symptom of a bad starting stance. Any Advice?