losing weight really fast 😭

ms
hi everyone, so first of all im a petite lady. Only 5ft tall and 25yo in two months, and all these years i never gain more than 100lbs no matter how much i eat everyday.  I have a high metabolism. 
I work in retail for 9 hours every day and that involved me walking/running all the time (that's my only exercise too).
So my problem is, lately i've been losing too much weight too fast. I'm usually 95-98, but im down to 92. I love to eat, but lately my appetite seemed to disappear. The changes in my lifestyle lately is i started taking bc pills last month(and im still bleeding) and since ive had to close almost all the time, i get home at like 2am, and ive always just been tired and exhausted. I also have school. 
Any tips on getting my appetite back? Or how to gain weight? I try to always have a snack or granola with me everywhere. Do you think the pills has to do with it? (I've been kind of moody/sad lately).