Tiny female

I recently rescued a tiny Persian female, she is 3 years old, only weigh 5lb.  I felt sorry for her when I visited the professional breeder, as no one wanted her.    so I took her home.

The breeder said she never been spayed, but never get into heat, and never interested in other cats.   I noticed when I got her home, all of my 3 cats totally ignored her, which is really strange, as normally they are very fussy about other cats, even kittens.

a few weeks now, she seems ok, however she eat a ton,, no matter what I feed, she will be there eating, possibly eat more than the total of my other 3 cats.   

another thing I noticed, she drink a lot of water, much more than my other cats. Despite all the drinking, eating, she is very thin, I can feel her vertebrate on her back.

other than these, she eats, sleeps and occasionally play, totally ignores my other cats

Please get her to your vet promptly  for a thorough exam - any time you adopt a new kitty, either from a breeder or shelter, you should immediately have them examined by your own vet.    If the breeder never bred her, then she should be spayed as soon as possible, providing your vet determines she is in excellent health.

I'm concerned about her weight, drinking excessively and voracious appetite.  Do you feel the breeder's premises were on the up and up? (i.e. not a hoarding or neglectful environment) - I don't want to make wrong assumptions of the breeder and her facility, but if there were any red flags about the premises such as sick cats, too many cats, crowded cats, deplorable conditions etc, then you have more cause to get your newly adopted to your vet for exam ASAP.

She may be eating excessively because she wasn't fed properly before. She may be afraid that the food source will disappear. She may also have had to fight other cats for food. Usually this behavior dies away when the cat is confident she will always be fed.

Wonder if this breeder lied to you about  her age?  Very old cats are boney...take her to the Vets asap for check up, shots, deworming.

Do you have any pictures of her to share? 

I did bring her to the vet in the first week, however she could not tell me anything useful .Having said that, the vets here in my opinion just want your money, not very good, all they know is antibiotic, quite a few times, I noticed they have to check book for the dosage, which really gave me bad impression.

as for the tiny girl, she just look like a normal chinchilla persion on the picture, but if you met her in real life, you will be surprised how tiny she is.

I do not know how many cats the breeder has, possibly 20 or so? most of them look very healthy to me and very pretty, just this tiny one sit in the corner, looking very sad.

A certified  Vet can confirm if she's fixed or if she's actually  a he  

The Vet would need to do blood work to diagnose thoroughly cost here is around 300.00.  

Please, get her back to the vet and ask for blood work to determine if her vital organ function is ok.  It may be only a nutritional problem, but you want to make absolutely certain.