Gotta echo U.D. here.
Headphones are nice, for personal listening, but's that's where it ends. They block out any ambient sound so you're not geting a true picture of your mix. I've got two or three incredible pairs of headphones but they're only used for editting or if I'm in a 'Sit down with a cold beer and please don't bother me for an hour'...kinda mood.
When I started mixing...about 30 something years ago..I made the mistake of depending on headphones, until I was enlightened to the fact that I wasn't getting a true idea of the sound.
..in short siahwayne, you will very seldom be able to replicate in a room, what you hear through headphones. I also agree with Gary that you may be overdriving, that along with not having a beefy bottom end speaker or bin.
Just my thots.... Good Luck