shit you're fine.
You want the sexy erotic type singlets like N2N makes? try internationalmale.com, mensunderwearstore.com.
Or the real wrestling singlets that HS and college wrestlers wear like eastbay.com has. They have charts that tell you what size you need for your weight. Pretty accurate way to do it to.
Be a good costume. I'd get the headgear, mouth guard, and kneepads too. I like the way they slide the pads down around their ankles between matches.