Sounds like she is in heat. Be very careful to keep her in and separated from any male cats.

I'd call the vet now...or check if there are any spay clinics in your area. The time between her heat cycles will get shorter and shorter and repeated heats can cause her and you frustration that could cause her to develop some behavior problems.

She and you will be happier once she has been spayed.

It is great you are aware and concerned about her. Aren't cats great?