I need a hair style for a flat forehead, long chin and a fat face when I smile, and suggestions?

I need a new hair cut that really flatters my face. I've been told by the "experts" that my face is between and oval and heart shape face. Its strange when I don't smile my face is thin and oval. When I smile or talk my chin drops down and my face becomes fatter and turns into a heart shape. My forehead is very flat and when I smile or talk my chin turns into a resse whiterspoon chin and is long and flat. I need a haircut that will hide my forehead and give me a better chin and slims my face down all at the same time. I was thinking long hair with bangs. Is this a good combo, or should I try something different? Also are bangs in and what if I look like a child with them?