I don’t really like my smile, what needs to be done to fix it? (photo)

I am a woman in my twenties, and I have confidence issues due to my smile. I always smile with a closed mouth because I don’t like the way it looks otherwise. I can’t really pinpoint what it is about my smile that I don’t like, I just don’t feel that it looks attractive. I am wanting to fix this in order to improve my confidence, but I don’t know what needs to be done to improve it. I would really appreciate any input. The 1st photo is my natural smile & the 2nd is a “say cheese” smile. Thanks!!