expected weight loss

I am 35 years old, 5'1', and weigh 117 pounds. I am currently working with a trainer. I want to lose 7 pounds. I have been working out and eating 1200-1500 calories a day for 4 weeks. I have only lost about 2 pounds (on a good day). Does anyone have any idea how long it will take to lose 5-7 pounds??