How can I grow my hair out?

Okay, so during the school year I straighten my hair everyday. I have biracial hair so its really nappy and frizzy when I don't. :/ A couple of years ago I cut my hair from my boob area to my shoulders and I HATE it. I haven't been able to grow it out because I keep getting fried ends from the iron. Now, since its summer, I want to grow my hair from my shoulders (its a little shorter when its curly cause my curls are so tight) to at least the top of my boobs. So about two or three inches. I've decided not to straighten it all summer in hope that it will grow!! Is it even possible to grow it 2 or 3 inches in like 3 months? If so, do you have any products, tips, or ideas that will help? :D Thanks!