I'm no doctor-- but there's lots of reasons anyone's period could vary. If you don't use birth control, if you are under unusual stress, if you are eating different, taking medication, or even changes in age-- how old are you? Does it feel different? Be more specific and think of the aspects of your life that might be different recently... it could have alot to do with an unusual period.

i have not had my period in six months, if i go to the doctor he saids all is normal but i know its not can anyone help?

Go to another doctor. Honestly, there is nothing normal about a six month lull on your period.

Trust me something is wrong when you begin to miss periods and your not pregnant. I've been missing mine now for 11 months, what a difference. I believe me not being stable with taking birth control cause it to make it very irregular. I go to the doctor next week, but you need to see a doctor ASAP!