First thing to do is stop thinking too much about weight. I am officially overweight based on BMI. Genetically I was severely underweight, 2/3 current mass, according to the same. In truth there was no problem when I was either way.
You were too heavy based on your assessment and now are too light. The thing you need to do is decide what you want to be regarding body constitution etc. and then work toward that.
Training and diet are best with variety, not total exclusion. If you enjoy cardio, do it and if it is burning too many calories based on your current diet you just eat more. The balance will be basically the same on your diet with a bit of occasional fine tuning, you just change overall volume.
I eat an absurd amount of food but when a lunch run burns nearly 750 calories there is not a lot of choice unless I want to starve to death.
So in order advice is
Decide exactly what you want, this will change over time but you need a target.
Decide what training you enjoy and come back with this and your targets to get some tips on best proportion that will help you achieve this.
If you want to gain weight you have to eat more, if you have the balance right for you that is great just up the volume. If the balance is off then you need to be looking at energy foods, complex carbs (starch not sugar) and sensible fats. If you are training more you will need more protein but this will be in balance not excess.