Excessive Weight Loss

Most people are only Too pleased to loose weight, but loosing weight TOO quickly can be harmful to the human body and your sudden weight loss problem need proper investigation.
There must be a root cause as to your sudden weight loss, and I would suggest that you 'pester' the medical professionals to come up with the answer as apart from Insulin/Carbohydrate balance there are also a vast number of possible medical conditions that can also cause this.
You don't say in your posting what amount and type of Insulin you are using or the time of it's use, but as you will know from being a Type 1 diabetic, the quantity and timing of the Insulin that you are using needs to be carefully balanced against the types of foods that you are eating (principally the Carbohydrates) and any exercise regime.
I'm not a Type 1, but hopefully there will be someone who can help you further.