How to look better in person?

I've always been pretty confidant about the way I look because I think I look good when I look in the mirror. Recently, however, I learned that when people look at me, they do not see what I see in the mirror. Instead they see a "flipped" version of that. Its kind of like what a selfie looks like when taken from an iPhone how it flips it. After "actually" looking at myself I've realized that I look horrible. My smile is awful and my left eye is longer and flatter than my right. This has really killed my self confidence so if anyone has any ideas on how to look better I would really appreciate it.

It just looks different because that's not what you're used to seeing. You look like you do in the mirror to other people (in a manner of speaking.)

You shouldnt feel bad because everyone has their insecurities okay? Not everyone likes every single detail about themselves and thats normal.
you can always start wearing makeup. Or if you already wear makeup, change up the way you apply it. You can also try dying your hair or getting a piercing to boost your self esteem.

Who you are isn't defined by your looks, it's defined by hour you are as a person

You do realize cell phone cameras are just as inaccurate as mirrors right? Seriously selfie can give you a different picture of who you look like different angles they are both just as inaccurate.

Yes.