Why do I look different in photographs and some mirrors?

I'm used to my bathroom mirror, so I use that to base my looks. When I look at other mirrors ( clothing stores, restaurants, etc) I look slightly different. Maybe it's the lighting? When I look at photographs, I look completely different from my bathroom mirrors. In fact, I look horrendous. In very few photographs, I look normal ( how i see myself in my bathroom mirror ). Why the drastic differences? Which one is the true image? The mirror or photographs? P.S. I heard that a person automatically makes themselves 10% more attractive when they look in a mirror, that it's unavoidable. Is that true too? Thanks