I do check it. and I have a notebook where I write everything I eat, the amount of calories.
So if it is water weight how do I do to lose it?

If it is water weight you need to drink MORE water. Sounds crazy but, that is why you are retaining water. Plus you need to watch your sodium intake. A high sodium diet will make you bloat up like a puffer fish. You would really be suprized how much sodium you can get in your diet especially with soups, frozen dinners, and deli meats. Which is a bummer, cause some soups and tv dinners are low cal! Boo!

So bananas have potassium, which is supposed to help flush out sodium. Try those things and drink MORE water....have a 1 liter bottle by you all day at work, try to drink at least 2 while at work and keep drinking while you are at home.

That's strange because I drink like 3 o4 lts per day and honestly I don't really cook with salt and I do watch my sodium intake :s

Watch those food lables though cause even if you don't add salt it still is in your food! Keep in mind your period will make you retain water too. From yesterday alone I am 3 lbs lighter, and that is all water weight!

I weigh myself every morning after I pee (or if you do the dooooody in the morning weigh after that). Don't weigh yourself during the day or you will have all the excess food and water on that scale too.

Women period soak up water, it sucks no doubt! Do some googling on water retention and there are a few good articles. Keep with it though it will take time. Remember it takes a 3500 calorie deficit to loose 1 lb. So if you are eating/exercising 500 less calories than you need to maintain per day, in one week you should loose one pound...again just remember your water weight fluxuates more than that so don't let it get you down!

Oh I know how you feel, but seriously I've learned to ignore the scale for a while. When I was working out with a personal I wasn't dropping any weight and I felt frusterated and defeated...but in the end when we measured me after two months of being with her I had lost 7 inches all around. Though I was at 158 I was a size 28! Seriously don't give up!

Also Cardio doesn't make you bulk up...IF you did weight it would but I was told by a professional that it's best to build muscle with resistant training in order to help with weight loss. Building muscle causes your body to burn fat away without having to do as much during the day and in the end result it'll take a little bit longer for the weight to come back on, than if you did strickly cardio. Which makes total sense because when I did just cardio for weightloss as fast as it was coming off...it came right back on just as quickly.

I have to agree with what other have said, you're probably just retaining water. It doesn't mean it's your fault. Everyone expects a steady weight loss at the rate in which it started, but in fact that would be unsustainable. You could try and speed things up a bit by maybe changing your work out routine (include more cardio) or adding some spices in your food and drink green tea. Cayenne pepper, ginger, chili powder and picante sauce not only make meals interesting without adding significant calories, but studies have shown that these spices as well as green tea have a thermogenic effect that helps burn more fat.

good luck!

And also, I have to agree with LilButterflyWings, scales do lie and can sometimes make you feel like all your hard work isn't paying off. In addition to measuring yourself I'd suggest getting rid of your traditional scale and maybe get the Quantumscale, it doesn't display a number, just the progress since you started your diet, so it's a good way to control your weight without feeling frustrated.
Stay strong, I'm sure you'll reach your goals.