AAAHHHH!! I've gained a pound! I'm now 140.4 lbs!

Whats going on?? I don't know what I'm doing wrong, I work out everyday, I've been soo good on Atkins (this past weekend was my first cheat in 3 weeks!) and I'm either staying still or gaining weight... this is very disheartening!
For the past 3 years I've hovered around 132-142lbs and I just can't get any lower.... I just want to be 120lbs is that too much to ask????

(Sorry, just asking the universe, not anyone in particular). It just seems that no matter how hard I try, how much exercise I get in, no matter what, I can't break out of the 130's....