I was a skinny girl and decided to start exercising daily. Since I started to work out, I found myself getting fatter. How?
I can only assume you know the difference between fat and muscle. I can also only assume you might be both bulking up and gaining weight because you are increasing muscle tone .. Muscle is heavier than fat.
However.. That may not even be the case at least not entirely .. You could be going through a hormonal change coupled with an increase in caloric intake which could plausibly be causing you to gain more fatty tissue.. It's hard to say .. It could be a combination of things.