I Am A 62 Year Old Female. I Weigh 188

I am a 62 year old female. I weigh 188 pounds and am 5' 6" tall. I do vigorous Aqua exercises and swim laps 3 times a week. I eat a healthy diet of lean protein, many fresh vegetables and fruits. I have eliminated most white carbohydrates and sugars (that are not in fruits and vegetables). I have eaten only 1,200 calories as suggested by My Fitness Pal for 3 weeks and have managed to lose only 2 pounds. This week I cut it down to 1,000 calories spread over 3 meals and saw no weight loss. I cut it to 500 calories and only 2 meals and finally lost 1.5 pounds. What am I doing wrong? I have been doing vigorous aquasize with water weights for a year and the pounds just stick with me. I eat very healthy.