If you are on the dining plan and have quick service for lunches, definitely do Flame Tree in Animal Kingdom. It is our (my) favourite in all of WDW and the ducks and birds will be good company. They sit right beside you (of course looking for a bite to eat) but good food and beautiful off the beaten trail table location is both peaceful and yummy!
Have a great trip. I think any mother, one with an ill child or not, we all deserve some alone time and time to be selfish. We spend all our time sacrificing for the better of our children and we too need to be pampered, and being alone is sometimes just what we need to recharge and be better moms overall.
DON'T FEEL GUILTY LADIES DOING SOLO TRIPS, THE MOM NATION IS BEHIND YOU

ENJOY