Be sure to exercise on an empty stomach, as it will make your reflux much worse if you exercise after eating. Before my surgery, if I walked on the treadmill after eating I would get terrible heartburn. Bending over, the same thing. Try to wait 3 hours or so after eating before you exercise.
If water is bothering you, limit it as much as possible. Little sips. Don't overload on it.
Just experiment and see what works.
Good luck! You're doing good things for your body!