What’s going on…

I’ve been with my bf for a year! I’m so in love with him, we’ve been TTC and this past month I was a week late and I felt extremely moody, I finally “started” only lasted two days and I’m still feeling this way. “Moody” “uninterested in him. I’m so scared because I have no clue why this is happening…….I don’t know what to do. I’m just snappy, I have not changed anything at all..