If all you are using to track your weight loss progress is the cheap weight scale you have in your bathroom, you are NOT doing so accurately. A scale alone is NOT the best way.
When performing your "weigh-in" you need to perform measurements as well. Your actual weight will fluctuate quite a bit once you’ve been on a weight loss regimen for a while. As you start to tone your muscles with your strength training and burn off fat, your weight will consist of more muscle and less fat (you are doing strength training AND cardio, right?). Since muscle weighs more than fat, you may find your weight goes up slightly while your waistline goes down. This is why regular measurements are just as important as stepping on the scale. I also find it very amusing to see folks stepping on the scale in the gym, fully clothed. Different shoes and clothing weighs differently. Your best bet is to step on the scale with only wearing your birthday suit.
Speaking of stepping on the scale, you should do so at the same time of day each time you weigh in. This holds true for measurements as well. As you go throughout the day, this will fluctuate as you take in food and as you expel waste. My suggestion is to perform your weigh-ins (including measurements) first thing in the morning. Hop out of bed, do your bathroom business, step out of your pajamas and step on the scale. Follow this by immediately taking measurements.
Sound like a bit much to do everyday? Don’t. My wife and I follow the six meals per day with one cheat day concept (no it’s NOT Body for Life, they weren’t the inventors of this concept). So our cheat day starts off with a weigh-in first thing in the morning. We would only do weigh-ins once a week.
Here are a couple of excellent Fitness Progress charts. They not only calculate your estimated body fat and BMI, but it also creates a couple of great graphs for you to chart your progress (make sure you look at the tabs at the bottom of the spreadsheet. We came up with our own which is very similar to these, but also included our workouts (so we could chart strength progress).
You may also want to invest in one of these:
Speedy Lizard 