Hi there,

I am wondering what the normal amount of sleep for a 9-month old Staffordshire Terrier is. She usually sleeps 12-15 hours a day, and it's starting to worry me at this point. She eats and potties normally. And acts normally, she's incredibly sweet and cuddly.

That sounds pretty good to me.

Mine are both adults and they sleep that much.

Dogs can sleep when they are bored or just have nothing to do, a trait that I admire :D
Seeing as how she is only 9 months old she needs her beauty sleep. If she is still eating normally and playing then I'd say she just likes her sleep!