My female was a stray. I was feeding her on the porch with the intention of bringing her in. I knew she had one litter which she abandoned or they died after a couple weeks. I never could find them.
My plan was to crate her, take her to the vet, have her spayed, shots, treated for fleas and worms and then bring her in because I have a dog and another cat (neutered tom).
Then one day I noticed her bleeding. My neighbor informed me she "left a mess" in his yard. I looked and it was fetus. I immediately took her inside and put her in my bedroom because my tom wanted to attack her and called the vet. She had another miscarriage on my bed.
Long story short. I did take her to the vet. $400 later it was determined she had no more kittens and they could not give her shots or spay her at that time. They did treat for fleas and worms.
Well, it was fall so I figured she wouldn't come back into heat any time soon. Since I work, it's hard to get to the vet. I did not know about the artificial light disrupting heat cycles.
She's in heat. What I do to minimize the yowling is just keep her in the bedroom all the time. The confinement seems to tone it down a lot. I'm in there at night and since I am now the object of her total devotion, she only has sporadic yowling sessions and I am able to get some sleep.
She hates my other cat and the feeling is mutual so no help there. Plus I neutered him very young and I don't think he has a clue what to do. Too bad.
My advice is never put off tomorrow what you can do today. A cat in heat is really no fun for you or her.