Is There A Supplement Or Safe Option To Gain Weight

Is there a supplement or safe option to gain weight for females? I am very naturally skinny from genetics I assume, but I have been on the lower end of my weight range recently; I'm about 105lbs at 5'3". I just feel myself being thinner than normal. Could it be from my birth control? I'm pretty sure about 5 years ago I was closer to 120lbs before I started birth control. I just want to know if there is a safe and effective way to gain weight? (I eat a lot a lot of food as well and it doesn't do anything) please let me know and thank you in advance!!