Molly is 13 wks tomorrow and she sleeps a lot! Honestly, she wakes up around 7:30, eats, poos, plays with a chewy for thirty minutes, sleeps until noon, wakes up, eats, poos, sleeps on and off until about 5, then she's active until about 9 then sleeps the rest of the night.
I used to think something was wrong with her-- but the vet says she is 100% healthy. She is growing like a weed, and that requires sleep. We joke that everytime she wakes up from one of her "marathon naps" that her feet look bigger.

I'm sure your fur baby is just the same!