I am 14 years old and I do not have my period! For the past two years I have had almost all of the symptoms of a period.. my sister thinks that it is because I am heavy but I'm not shure?

You really have to talk to your doctor. 14 and no period is not unheard of. But if it is your weight causing the delay in your first period then talking to your doctor about healthy weight management is really important. Is your sister concerned that you are over or under weight?