I want long hair but..?

Okay so the last time I cut my hair was in December! My hair went from just above my shoulders to my chest in six months but I also stopped straightening my hair except my bangs for awhile but I got a hair cut today :( because my hair was fried and kept falling out now it's short again and the hairdresser didn't give me ling swept bangs, instead I have to deal with short bangs, well I really want to grow my hair out and keep it healthy... I like to straighten my hair when it's short plus I have layers which a short now :( what vitamins should I take? Can I take more then one kind? Help my hair grows slow! I haven't had ing hair since I was 9!