I don't mean to alarm anyone, but I have to be honest. When I first say this composition and expression, I thought the character might be..(Gulp) dead.. The pose has a "frozen" aspect to it.. See if your local zoo or animal park has a resident serval, and spend some time watching and sketching. Cats usually have a specific way they sleep. It generally has to do with conservation of body heat and temperature control. I like the lighting, and the character is well done indeed. I just think you have to spend some more time looking for a slightly better overall express of both a (wild?) cat in the sun, and the general feline nature.
She's supposed to be nuzzling up in the grass xD Its something my cat does, it wasnt supposed to be entirely realistic, more like adding human expression and posture to an animal, something I've always done