no she really looks like her size should be. but i do know they they are all sizes. We've had alot of cats over the years. I used to have one that was small for his age then i have one right now that's 3 1/2 year female and she weighs 16 lbs. She's been spayed and gets no exercise....so she eats the cat food for weight mangagement now....lol
we had one outside for 12 years he weighed 17 lbs and he got alot of exercise. I don't think you can stunt their growth, they just come in all sizes.
our neighbors cat stays at our house now and she's about 5 monthes old and that's about how big she is too.
just love them and they will be fine.