Hi I just wanted to share with you that my mom went through the same thing at around the same age. The doctors after many tests attributed it to stress, diet change, and early menopause. They told her she was very healthy otherwise. They couldn't find any changes in her levels either. Don't worry to much. It didn't help my mom at all. They say that so many little factors combined can delay and change cycles. Good luck. I hope I eased your worry a little.