I believe my cat is pregnant, around 4 weeks now, she gained weight, her nipples are pinkingup and her abdomen is bigger than before but lastnight, i saw her with a tom mating, she screamed and roll on floor, is that even possible that she is still in heat even pregnant?
Cats have a multi-chambered uterus and can be fertilized by multiple males to gestate at the same time. It's not like humans; once a human is pregnant, they can't become even more pregnant, but a cat actually can and being pregnant doesn't prevent additional kittens.
Please keep your cat away from intact males until she has given birth and been spayed. If she attempts to mate in the meantime, it can result in her being injured or pregnancy complications.