Diane is right on the money with adding strength training!
Strength training will add on muscle. At rest, muscle burns more calories (as lean mass) than other tissues. Basically, with strength training you turn your body into a calorie-burning furnace!
Oh and you get a second benefit too - your muscles get tighter and toned (you won't turn into Arnold S. unless you're lifting like crazy!). This gives your body a more trim appearance and your clothes actually will fit better.
No equipment? No problem! You can do push-ups, crunches, arm curls with soup cans, chair dips, squats, lunges, leg lifts, etc. All of these can help build strength without owning a single piece of equipment!
If you're doing the exact same cardio every day, start to switch it up. Include intervals. For example, if you're walking 30 minutes...walk 5 minutes at your regular pace and then walk 1-2 minutes at a super fast pace or even a jog. Challenge your body to do more than what it has gotten used to. Cross train - do the elliptical, bike, stairclimber, swim, or even play a vigorous game with your son in the backyard.
Don't go on a 'diet' but make smart choices about what you eat. Go to www.sparkpeople.com and start logging what you eat. You'll get helpful hints on how many calories, carbs, fats, and proteins you should be consuming each day. People who journal their food intake are FAR more successful and lose MORE weight than those who do not.
Make sure you are eating enough. If you're cutting too many calories (i.e. not eating more than 1200 per day) then your body goes into starvation-survival mode. The body freaks out thinking "I'm being starved, so I'm going to hold on to what fat I do have with dear life in case she is going to starve me forever!". Try to eat 3 meals a day with two snacks in between, and your caloric intake should be between about 1400-1600 per day.
AVOID all pills or special gimmicky products! They are a band-aid solution to a long-term issues you're wanting to change. Sure they might work, but you'll put the weight right back on as soon as you're done with the product. If everyone's 'special weight loss secret' product worked, would we be a nation of obese people? NO!
You've done such a good job - all you gotta do is step it up a tiny notch and you'll find yourself blasting through that plateau!