The first thing is that whatever method or madness you use to lower your weight, there are no guarantees as to their effectiveness. Just as there are all different kinds of people, there are many different methods.
What works for me may not work for you or vice versa. You have done the first thing right and that is to seek help.
The basics for losing weight are input (what and how much you eat), output (exercise/activity level), and metabolism (how your body processes what you eat).
If you are exercising like you say you are, then you will need to look at your caloric intake and see if you are eating more than you are burning off.
When I started losing weight, I used a supplemental system. After 10 days, I incorporated walking and now I am up to walking for 2 hours averaging about 4-5 miles. I recently started at a fitness club to start building muscle and burning fat.
A good place to start is:
Free Diet Plans at SparkPeople
You can get a free diet plan based on your statistics.