I'm 163 at 5''11 right now (damn BJJ stops any unnecessary muscle gain) and I'm probably eating at least twice as much as you. It might have been ok if you were sedentary, but you seem like a pretty active guy, so my advice is to eat more!
I tried the low carb thing also, it took me three weeks before I crashed completely. It's really not made for people who are into sports that tax the glycolytic pathway.
Do you cheat much?