Having issues with tummy

kasey98226

I am a littler person (4'7") and weigh about 100-115lb on average, and 26 years old. I still have a bit of a prominent tummy and tushy. My arms, face, and legs are rather slim, but I am not toned anywhere because of arthritis in my wrists and tendonitis in both knees. I want to loose 15lb to see if my tummy goes a little slimmer as I do ab exercises, and about 30-40 minutes of low impact aerobics. I get conflicting calorie and work out information based on my height. I even had one "calculator" tell me error, I think it thought I was lying about age to height.
My friend is 5'8" and 150, and her "goals" are the same as mine, and we work out together. She has been loosing, and doing great, but I feel like my measurements as stagnate even when I loose some pounds. If it matters, I have had 2 kids naturally.
Any advise?
THANK YOU!