Unable to gain weight. Doctor for this.

I am 22 years old 163cm tall and currently weight 46 kgs. I have a petite figure and I've always been around 50 kgs, however I used to always eat healthy and exercise to keep my form. It has been 4-5 months and it doesnt matter how much I eat I can't gain weight. Major diseases come up when I look up "unconditional weight loss and unable to gain weight" on google so I decided to consult a doctor. I did a general check up and several blood tests. It turned out that I was lacking Vitamin D and I had hypoglycemia. The doctor prescribed vitamin d pills and told me not to take any medication for hypoglycemia other than eating healthy meals every 1-2 hours. However I am still very concerned about not being able to gain weight. I know this is every girls dream but eating unlimited amount of carbs and not exercising and still staying at 46kgs makes me feel like I may have a condition doctors havent found out about. I wanted to consult you to see if you think I should see a doctor for this.