If he was under the water dish, you may have to change your hides to fit him more snuggly. BP's like to feel their hide all around them, and he is no exception. I found that the clay pot water dishes work very well for that.
As to his age.... I'd say he is maybe 4-5 months old. I'm just assuming you've had him for 2 months, and they kept him for 2-3 months before they sold him. I'm not very good with the age vs. weight of young ones, but just an idea.