I am 5'4" and even in maintenance I gain weight if I consume more than 1500 calories a day even though I exercise at least an hour daily. 2000 calories sounds like it may be too many. To lose weight the amount you eat is at least 80% and it is great to exercise to lose weight but it is near impossible to lose weight if you do not lower your caloric intake.
Do not give up. Try making the calories you eat come from clean, unprocessed food.