Remember that your weight can vary a lot day to day, you might be retaining weight that wasn't there last week (water and err other stuff) particularly if you have recently changed your diet radically.
Water retention particularly is far worse for women than for guys. I've heard reports of up to 5lb for blokes and 7lb for women, though I can't cite the source right now so that's from memory.
I've seen it where I've had a few large but low cal meals (veggie stew with cauliflower "rice" & huge salads) in the days preceding a weigh-in, and had less "loss" than I expected but the next week had a much larger loss...
Which is why I prefer to focus on other metrics and only use the number on the scale to keep score.
My main focus has up till now been my waist size. Now I'm getting more interested more in my following my chest size now I'm closer to my over-all target.
42" jeans(25/01/2013) 40"(28/02/2013) 38"(20/03/2013) 36"(25/05/2013)
Down from 60" waist jeans since June 21st 2012.
Still keeping to my 26" jeans, but they are too tight for comfort. too many tasty things in the US, and over Xmas.
Onwards and Downwards! http://www.menu52.com/