Do Mirrors Lie?

Questions of perception have always plagued me. It always disturbed me that someone as evil as the current pope, for instance, could actually believe that he is a benevolent force in the world, even though we he was a "reluctant" member of Hitler Youth and he regularly preaches hatred towards homosexuals. Or that people with extensive cosmetic surgery could think that their plastic lips and frozen foreheads could possibly be attractive and youthful looking.
The perception of one's physical self has been a particularly problematic concept in my life. Recently, I've been increasingly more at ease with what I've been seeing in the mirror, because I'm slowly losing a bit of weight and have been fitting into clothes better. So the typical female disgust with my appearance hasn't been at the forefront of my mind, thankfully.
Until this morning, however. Unfortunately, the pictures taken at a family party yesterday reveal otherwise. Needless to say, I was mortified by how fleshy and over-weight I looked. Which brings me to the point of this post: how could what I see in the mirror differ so vastly from what I look like in reality? Granted there are the postmodern arguments that a photograph is not actually reflective of the truth, but I am of the school of thought that believes if a picture isn't photoshopped, it is an accurate visual representation of that millisecond of time. As a rational, pragmatic person, if terrifies me that what I think is physically acceptable (my outfit, or hair) when I see it in the mirror may not actually look nice to any other observer. And I'm not talking about fashion, I mean appearance, in general. And short of developing some sort of giant instant-Polaroid picture system, I don't know what to do to remedy this discrepancy between my mirror self and my physical self. This isn't even a unique existential conundrum; I cried about this many a time when I was fifty pounds lighter than I am now. Is there a way to align the two perceptions?
I know this discussion makes me seem terribly superficial, but it would be a lie to say that our physical selves do not play a huge part in shaping our identities. I can only hope that the rest of society isn't as critical of my appearance as I am.