Thanks for your reply. It's like you first said - if it comes the 28th, it will be the 21st the next month, the 14th the next and so on.
Your post is very comforting. I normally post on the PTSD, OCD or Bipolar boards because I've been having very bad symptoms for more than a year. My stress level and screwed up brain chemistry has been wreaking havoc on my body and mind. I had hoped this was the problem with my cycle, but wasn't sure.
Thanks so much.