The only advice I can give is to embrace it. When you think you look good in the mirror, it's not because you look any different than the day before, it's because you're in a good mood that day, and it changes how you see yourself. You'll be in a much better mood on a regular basis if you embrace your perceived flaw.
The real question is why you think it matters. Does it come down to attracting women? I can't say this enough.. It really doesn't matter. I served with a guy that was ugly as sin. I mean, his head just wasn't even shaped right. Not a good looking guy at all. BUT, he scored with women constantly.
For one, he dressed really nice. I see people all the time that aren't very attractive, or they're over weight, and they dress the part. They dress down probably because they don't feel good about themselves, and they make them look worse. Like ZZ Top says, "every girl's crazy 'bout a sharp dressed man".
Another thing is he had a pretty good body. That in itself helps any guy feel more confident, but it also attracts the ladies. Would that make you a butter face? Yeah, maybe. But I'd rather be a butter face that's getting laid, then a lonely schmuck that's sleeping alone.
Finally he had a lot of confidence. At the bars/clubs, he didn't sit around feeling sorry for himself. He got out there and talked to women. He had a good time with friends.
I'm not a great looking guy either, but I've been lucky to meet a lot of women. I've even dated more than a few girls that were out of my league. It's really all about how you carry yourself. Thankfully women are less concerned about physical appearance than guys.
The secret of success is honesty and fair dealing. If you can fake those, you've got it made. - Groucho Marx