It sounds like he is getting over 11 hours of sleep, when you factor in his nap, so I would think that he is getting enough. Studies are now showing that not everyone needs the same amount of sleep, some need more than average, some need less. My seven year old never seemed to need that much, his mind was too busy to sleep, while my four year old can't get by without enough or he gets crabby beyond belief!
What I would be concerned about is YOU. It doesn't sound like you are getting enough sleep or enough of a break for you time. Is your husband around on the weekends? My husband works crazy hours and we hardly see him, so I can sympathize with your feeling like a single mom, it is tough, isn't it?