Thought I was getting AF but it stopped??

My husband and I have been TTC for about 6 months and this month I really thought we succeeded since I've been feeling different and more exhausted. then I was disappointed when I started lightly spotting Thursday and bleeding enough for a tampon Friday. I still never filled one throughout the day so it wasn't overly heavy but I was sure it was AF. Then Saturday I was back to light far in between spotting so back to pantiliners and today nothing. I have regular 5 day periods usually heavy enough to go through an entire box of tampons of 18 at least. has this happened to anyone before.