my cat pregnancy

Question
Hi doctor
As you know i have 4 Persian cats.2 males and 2 females.one of my females is Fifi.Fifi is 16 months old now ,she is a red Persian, very beautiful. but she is a bit odd .she was very small and weak when she was a kitten.once a vet told me it's due to her position in her mom's belly.she staggers like a drunk also.not always,sometimes when she is playing or running.it's a part of her nature I'm afraid.
when she was 7 months old(she looked like a 4 month old kitty)surprisingly her first mating call began.she mated with her own father.i wondered how can a tiny cat mate!after 3 weeks it seemed that she is pregnant.but after one month the big belly get normal after some contractions.the vet said it was a false pregnancy.
soon she mated with her uncle,this led to a pregnancy.but she miscarried the only kitten of her litter exactly one week before the big day.she was still very tiny.
but after this miscarriage she gradually enlarged.now she is in a normal size and looks very healthy.she is in her prime i think.
But there is a problem,after the miscarriage she has mated two different times with two different males.but she didn't get pregnant.the recent male was not her family member.i mean it was not a case of inbreeding.but again she didn't get pregnant.she starts her mating call about three weeks after each mating.i'm very much worried about her because i do want to have her kittens at least one time.i don't want to spay her before a healthy litter.i wonder where is the problem.why she can't manage to get pregnant?has she became barren?she seems very healthy and she has proved that she has the capability to get pregnant.so, what is the problem?is there any chances of getting pregnant in future matings?O doctor please help me!
sorry for long story but i think it was essential.
thanks a lot.
Soheil

Answer
Hi Soheil
You may have a cat that is barren that is completely infertile, or possibly a low fertility state. Now if she is not barren and there is no reason to presume she is, then there are ways to encourage her to increase her fertility. First ensure everything you feed her is completely fresh, if you feed her kibble then consider giving her cooked chicken, cooked meats and of course make sure she has necessary vitamins and minerals. Also give her bottled water not tap water.
Go with this for the next four to six weeks and watch her. Do not attempt to mate her on her next call but let her call and then keep feeding her. On the following call consider mating her with a non related cat. Don't try to mate her with any father, grandfather, uncle or brother.