Vet has just called back, he did say that if she had a problem with thyroid, she would be heavier as apparently, dogs gain wait and cats loose weight with thyroid problems
Anyway went over her behaviour and he asked me regarding vulva swelling, etc etc, and she has no physical signs
He did say sounds like she could have had a silent season and said that with bitches that have silent seasons are at an ever greater risk of Pyometra
, so he advises that I get her spayed, which is what I was going to do after she had her next season
Oh dear, looks like its going to have to be done sooner than I expected