How often are you feeding it?
I;ve had mine for almost 2.5 years. At first it deflated several times a day coping with the increase in light. But after acclimation(about a month all told) quit doing that.
I would not feed it heavily....maybe once a week if that. When I fisrt got mine I fed it frequently...which actually stressed it out. Now I rarely feed mine at all. Maybe once every couple of months.
If you're concerned about it bleaching, you might consider reducing the photo period some. But to be honest with you, if its behaviour is as you described, I wouldnt worry too much. It has the capability of moving if conditions arent right for it, and its not deflating...let its behavior dictate your assessment of its condition.
Also, I have seen a white based Ritteri that was in fantastic health. It was easily 20-24 inches in diameter and had been in captivity for over 12 years by the same owner. The thing was a beast.
Nick