You need a complete, balanced diet. You are literally starving yourself and yes, you will eventually lose weight, but it will take a horrible toll on your body, over the long haul.
You need to determine the number of calories you need each day, just to survive, then decrease that by approximately 500 calories/day. I guarantee it will come out to more than 600-800 calories/day.
You don't say what those calories consist of - if a candy bar (about 240 calories) is part of your diet, you're not likely to lose weight. Taking laxatives after every meal is very dangerous.
You need to be eating lots of fresh/frozen veggies, fresh fruit, whole grains, low/no fat dairy, lean meats, nuts, seeds, beans. If you don't adopt a healthy lifestyle, you will only gain back whatever weight you lose and will ultimately end up on a weight loss roller coaster, which can/will destroy your health, as you get older.
Additionally, stress can cause inability to lose weight, as well. Since you are obsessing about your weight, you would probably be pretty sure that cortisol levels are high and high cortisol makes it very difficult to lose weight. You might want to think about some counseling, in order to put things in perspective and get on the right track.
You need to make sure you don't have underlying health issues, such as hypothyroidism, insulin resistance, or PCOS - all of which make it difficult, if not impossible to lose weight. You can only determine this with proper medical testing/evaluation.
sounds like you're kind of starving yourself. have you cut the sugar and high frutose corn syrup? bread? potatoes? all that jazz? Maybe you haven't lost any because you're too stressed out about it.