It's impossible to enjoy sex if you're more concerned about how you look than enjoying the pleasures of the flesh. If you're not present in the moment you are shortchanging yourself and your partner.
It's hard to convince a woman that a man sees her differently that she sees herself. They are not nearly as concerned with the flaws as you are. They are turned on by your passion, your imagination, your enjoyment – not your perfect perky breasts.
Sex is too important not to give it your full attention. Love the pleasure that your body can provide and stop worrying how your butt looks from every possible angle