How long do false pregnancy last in cats?

So my 11 month old cat escaped outside when she was in heat on the 1st of january. It was her first heat. I caught her with the resident cream persian cat that the owner stupidly lets outside anf hasnt neutered. I ran outside to break them up but it was too late. She was rolling around so i took her inside. She clearly ovulated because she didnt come into heat again. I took her to the vet to see if she was definetly pregant because her nipples had pinked up but the vet said she wasnt. Its now week 5 and she looks normal and only displayed the early pregancy signs. I had her blood tested for any diseases as well and she came out clean thank god!! My question is will when will she come into heat again. The vet said soon but wouldnt give any set date. Her last heat was very pronouced but i havent seen any signs and its been over a month now. How many days do psudopregancys last in cats? And do u have any idea when she will come back into heat? Just so u know we would like her to have one litter as she is a pedigree british shorthair. I think its fair to let them have one and then get them spayed. I know there no proof this benfits them but its just my view as a human. She we be promptly spayed after. Thank you

And also the vet confirmed it was a false pregnancy saying that cats ovulate after the mate and that the sperm may have died while waiting. Or maybe they never mated to begin with but the brain thought they did.

This happen to me as well my neighbor let's her cat out and he gets all the neighbor hood strays pregnant so there's cats everywhere in the beginning of December my cat that was already supposedly fixed when I got her got out on the 2nd and the 10th and I heard her crying in the back yard so I went out to look and he was on top of her and now she's pregnant and due any day she knows what her cats doing but she will won't get him fixed

That's ashame good luck with the cat litter. But my questions sill not answered

The moms don't begin to 'show' until 5 weeks along.  How could your vet tell if she was or wasn't pregnant that soon?

He palpatated and did a ultrasound to see if he could pick any fetal heart beats up. The scan sounded nothing and he felt nothing which lead him to say its most likely a false pregancy. I took her to the 2 days ago.

She might be pregnant.  Give it another week or two.  How far along would she have been when you took her to the vet?

She would have been exactly 5 weeks

Ok, so not pregnant.  @StefanZ might have the answer.

Ithink false pregnancies are usually roughly as the usual pregnancy, perhaps somewhat shorter.

Okay thanx guys. So do u think u could give a esimate for how many days u think it would last.

I doubt there is an exact number since it's psychological. It will vary.

Lol it doesn't matter now she's come into heat Definetly now. It must of been pro-estrous