Homesteaded cat

Question
As we worked on our newly purchased home in mid February, the resident female cat was in heat.  (I wanted to get her spayed but didn't have anything to use to catch and transport her.)  We let her stay around as she got "fatter" and "fatter."  Two weeks ago, she disappeared for about 3 days and suddenly became rather thin, and we assumed she had kittens under our house.  She would attack our legs if we walked toward the opening.  Now, however, two weeks later, she acts like she is in heat, again.  There are two strange cats hanging around, and she's doing the mating thing.  It looks as if four of her teats are being used, but that's no guarantee since we can't handle her or look really closely.  Is it possible for her to be nursing and in heat, or did she most likely lose the kittens?  If she's in heat, I need to get her to the vet to get spayed if I possibly can.  Thank you for your help.  

Answer
Hi Phylis, Yes I would guarantee that your cat is in heat. Some cats come in heat the day the kittens are born! So she is most likely getting bred and it is most likely that she has a nest of kittens somewhere. The kittens would be too young to have mom gone for 24 hours to get spayed. Your best bet would be to talk with your vet about this. If she is nursing he may be hesitant to spay her right now but your vet will let you know how far pregnant she can be and still be able to do the spay safely. My guess would be to bring her in to get spayed in 2.5-3 weeks. At that point her kittens will be fine on their own for a bit and she will not be too far pregnant for the surgery.
Teresa