Help, Girls and Doctors help needed?!

That's perfectly normal, your body takes years to get used to it and it is not going to be the same every time or for each person. I started mine when i was about 13, i'm 17 now and they are still all over the place, some times i'm heavy and the next month i'm light and then they last for 4 days and the next a whole week. Plus they usually start on different days of the month.
You have nothing to worry about, it's perfectly normal :)

are you eating enough or under stress? those could make your period not show up.

maybe see a doctor