get your body fat tested. at your size, that's going to be a better indicator of what kind of weight you have to lose than the number on the scale. if you're already under 20%, then you just don't really have any more fat to lose. if you're over 30%, then you do have some to lose. the closer you are to 20%, the less you have to lose.
the other thing to remember is that your weight can vary by 5lbs per day. and at your size, 1/4lb per week in loss isn't unreasonable. if you'll note, 5lbs is 20 times 1/4lb. which means that even if you are losing right at that 1/4lb per week clip, that daily variance is enough to obscure any progress you may be making for quite a few weeks. so you really need to be shifting more towards a long term outlook on where you are rather than an easily notable weekly progress. this is a point where it really can take up to six weeks to see the results of your work, and every time you start changing things up it resets that clock.
you should also be looking to other indicators rather than just the number on the scale. bodyfat is one, take some measurements, and try and find some sort of fitness test to take as well [women's day/health/world had a great one a few years back that was a sprint, sit ups, jumping jacks and a chart that told you where you were based on your age. i have the paper copy of it somewhere and i'll try and remember to dig it out and find it online for you]. these sorts of things can be a better indicator of your overall health right now.
and i will say this. for me, at maintenance, in order to drop an inch around my waist, i need to gain ten pounds. and it usually comes in the form of an inch or two of muscle buildup in that area, and then my waist starts going down. when you're starting at a healthy weight, the rules are a little different than when you're getting to a healthy weight.
-google first. ask questions later.