Hi Chris
There's no definite way for me to tell you for sure but its all looking a bit suspicious that she might be pregnant, in which case I guess she was probably older than 4 months when you got her. The pregnancy length for cats is around 63 days so you can count down from when you got her! Of course it could just be that she was underfed and is making up for that now and getting fatter. If she is pregnant her teats will become very prominant near the end of the pregnancy and you just might see movement of the kittens in her belly. Keep feeding her, she sounds like she needs it and certainly will if she is going to have kittens.
Cathy Wickenden BVet Med MRCVS
Barton Lodge Veterinary Centre
1 Midland Road, Hemel Hempstead, Hertfordshire, HP2 5BH
Tel: 01442 216048 24 hours
[
www.bartonlodgevets.co.uk]