I will start this text by answering the old famous question: "No, you will not get rid of your extra belly through abdominal exercises only. A well developed abdomen is a result of many factors such as balanced diet or food reduction, correct exercises" all in the right amount -, discipline and genetics.
Diet: I have to repeat what we all have heard or read everywhere and, unfortunately, there´s nothing new, no easy way out: for nice abs we have to watch out for what we eat, that is, avoiding greasy foods, sweets and sodas, choosing non-fat meat, eating carbs (yes, on a balanced diet), vegetables, fruits. All of that, of course, trying to make various small meals through the day (I´m sure you´ve heard about it, but never tried, am I wrong?). Of course we can eat our favorite dishes, but with moderation and on weekends and/or special occasions. A nutritionist will manage to distribute your meals efficiently, making you lose that extra tommy and keep your muscles - a bad diet will make you lose all the muscle mass you have worked so hard to gain.
Exercises: do you really work out or you just pretend you do? The human body has an adaptation capacity that, despite varying from one person to another, always keeps one characteristic: it cannot stay for too long on the same training program!!! Therefore, if you are on the same speed at the stairs, for example, if you´re doing the same abs series for 3 months or the same weight lifting series for 5, your training program is not having the same effect on your body. Ask your instructor/ personal trainer to modify it by changing the speed on your stairs, giving you new exercises, different abs. work your body and it will pay off giving you great muscle definition.
Genetics: there’s a popular saying in Brazil that goes: "if you were born a lizard you will never become an alligator". That means there is no point in trying to take your body to lines it cannot cross for genetic reasons. However, in the space between genetics and what you aim must be: discipline, lots of training, and personal effort. In my years of experience I have accompanied some people who got extraordinary results just by changing their diet and training program.
Abdominal exercise: 5 series of 1000 abs a day? Every day? Something is wrong, I assure you are wasting time at the gym. Abs must be worked out as any other muscle; hence, they need a certain level of difficulty in execution. Therefore, ask your instructor to change your exercises so you will do less repetitions with a little higher level. Besides, take a rest from the abs every other day; everyday work is not good for the muscle.
Good practice and take care of your diet! It is fundamental for well defined abs!