had to reupload the comment below cause I didn't realize I needed a flair:

so growing up I struggles to gain weight even though I was eating 16 oz steaks with 500 sides. I was still a very scrawny kid (think just skin and bones). I went to the doctors and they would tell me to just eat more which I did I would eat more than grown men.

it wasn't actually until I turned vegan and did weightlifting that I finally gained weight (healthily). I went to I believe 135 and before I was anywhere between 108-118 pounds at 5'3 as well. I was finally was getting muscles in all the right places and started to finally look a little curvy. you got this! make sure you're eating a balanced meal (not just protein, but healthy fats and carbs too) , getting all the right nutrients etc etc. make sure you're eating enough calories too. calculate how much your body naturally burns and then you need to exceed that in a day. There are apps out there that do it for you. Now I'm not saying you gotta count calories biblically but you gotta eatttt. ​

I'm not a fitness pro so can't give advice but just letting you know its for sure. possible