Hi, I'm Worried About Some Unintentional Weight Loss. I'm An

Hi, I'm worried about some unintentional weight loss. I'm an 18-year-old female. Here's a timeline of weights:
June-138lbs
August-127lbs
Dec 10-127lbs
Jan 15-118lbs
I stopped my usual moderate yoga practice in October, my only physical activity. I only weighed myself a few days ago because I felt as if I may have gained some weight because I have been eating so unhealthily and been inactive. However, I should mention that my body seems much the same since losing weight. My clothes fit the same way as always. If the scale didn't tell me I was losing weight, I wouldn't think I was.
In December I began having light-moderate acne problems, which have continued through the present. I also had an extremely heavy and long period in the middle of my cycle in December, though my period had been well-controlled up to then. I am on the progestin-only birth control pill ("mini-pill"), Lo Loestrin Fe 1-10.
If you think it's nothing, that's perfectly fine.
Thanks,
Hannah