I am 16 and haven't had my period yet. should i be concerned?

I'm 16 and weigh 240 but it's not all fat. i have gone to my doctor and she said to loose some weight and see if i get it but it isn't working. i have small breasts and am not pregnant. should i get hormone pills or birth control or something to see if i get it? my family says it's a blessing but i'm not sure, i don't want there to be something wrong with me.