Short hair wanting long hair

Help!! I have shoulder length hair but I really want to make my ahir grow longer than that. When I was younger I had hair to the middle of my back, however; when I went to school I decided to go for a new look and cut it. I received my first which in turn also brought out all of my temple hair. Now that was two years ago and it has not gotten back to that lentgh since then. I am getting married next year in June and would like for my hair to return to that length for that occassion and for good.