oh frustration!

on friday, i weighed myself and i was down 8lbs!! i was so excited, i felt like i was back on track after my TOM, but now, for the last 2 days, i've consistently weighed in at only -5 to -6lbs again. argh! i know i am doing things the way its recommended, and i expected to hit a plateau, but i expected it after 2 months, and maybe 15-20lbs, not after 3 weeks and only 6lbs! my BMR is around 2050, and i am consistently eating between 1800 and 2200, most days i am a little under 2200, more like 2000 on average. i am trying to be more active in my normal routine, walking a lil farther each morning from my car to the building, taking my dogs for walks every few days, swimming when i can, etc..., and also doing 4-5 days at the gym doing cardio and weights. my bf% has gone down about 2%, so i am very happy about that, but i expected to loose a little more than this by now, especially since i was down 8lbs just 3 days ago.