Smartie has a false pregnancy every time she has a season. Whilst it gets quite distressing, so far we have had no complications. First time she had one, I was worried sick, and like you, rushed her off to the vet, convinced she was dying (I always was a drama queen!)

Generally she now just carries her favourite toy welly (same toy every time) does alot of whining, digging, panting, and guarding, but within a week or so it's passed. Her teats have always become very swollen, and we were told not to tickle her belly during this time too.
Like you, I don't want to have her spayed, and have come to notice the signs now, and reassure her alot during this time.
Good luck whatever you decide x x