Right, time to give you a lesson, you are 45kg, unless you are under 4'5" (legally a dwarf) you are underweight, bordering severely-underweight. It is the result of an eating disorder and from the sounds of things, your dietary habits are questionable at best.
Firstly, I want to make this clear anorexia is an eating disorder. Anorexia nervosa is a psychological mental disorder characterized by self-starvation and extreme dieting. As you have said you wanted to lose weight and you will not eat normally until you achieve your goal, the fact you have reached a very unhealthy low weight indicates you have anorexia. However, I am not a clinical psychologist, so I won't pass diagnosis.
You have an eating disorder. Get that clear in your mind before
This is what you do: You start to eat 3 separate meals a day, you balance your protein as 1.5g per kg of bodyweight, and your carbs at 2.5g per kg of your bodyweight PER DAY. You also make sure to consume at least 1900 calories a day. This is a low amount of calories but your body isn't used to lots of food from the sounds of things.
You need an exercise routine to tone out your body, and to stop an excess fat. Start with light weights, 8-10 reps and 3-5 sets of exercises, this will allow for the most hypertrophy (muscle growth) and allow to better tonality in the muscles.
Women typically carry more fat around the abdomen and the hips, this is natural, and genetic, you cannot change it, but you can reduce the amount and put on muscle in those regions to appear slimmer.
Seriously, you clearly know nothing about healthily losing weight and it has resulted in a clear eating disorder. Eggs, Chicken, Rice, Pasta, all have to be your best friends now, in order to reach a healthy weight and get the body you want.
I know this seems harsh, but I've been where you are, and I recovered.
See your doctor again, be honest with them, also see a dietician, they will help you. But stop kidding yourself, your weight is unhealthy, your BMI is only skewed in the case you are extremely muscular as muscles are denser than fat.