Project Weight Gain

So I am 5’6 1/2 and I weigh exactly 100 pounds. Give or take four pounds depending on the day. I have been at this weight for three and a half months. My BMI is VERY low. I have two reasons for my weight being so low. A.) I was born small and have a fast metabolism. B.) I was taking a medication that caused me to lose 30 pounds. The first picture (I’m the one in the red pants) is me before the medication. And the last three are me now. I am going to try to get myself up to 115-120. My plan is to workout(lift weights and things) and I plan on eating a lot of protein and carbs. lol I’ve had five pb&js in two days. I stopped my medication two days ago. I am going to try to post weekly on my progress. Feel free to stick around every Sunday and see how things are going ! :)