Calories Lose weight?

[Emoney]

Hi, im 20 and weighed 164.5 lbs. I recently went on a diet for the last 30 days. i dropped my calorie intake from 2800 to 1500 per day. I lost 11.5 lbs in 23 days which meant i lost about 3.75 lbs a week. According to the computer its unhealthy to lose more than 2 lbs a week but, its not like i starved myself. I cut out cheese, candy, soda, fatty foods and replaced it with oatmeal, lean meat, fruits, vegetables, non fat milk, granola bars, eggs, tuna and so on. Basically high protein low calorie diet. My new weight is 153 lbs, but im still not were i want to be. I never actually did cardio through the whole diet. Should i keep going solely on the 1500 calorie per day (will i continue to lose weight now that i am thinner) or add cardio to continue weight loss. My goal is to lose most of my body fat. You know, rock hard abs. Oh and i lift weights 4-5 times a week.
Oh, by the way how many calories would i need to maintain my new weight?