Is this normal if I'm on the Pill?

I'm 14 years old. My mom put me on the birth control pill about a month ago because I had VERY intense, breakthrough bleeding and to treat my mild acne. She is an OBGYN so there are other health benefits also. I was wondering though, I'm having a very light bleeding "spotting" between my periods. I'm on Loestrin 1/20. Is this normal? I'm getting really nervous about it, even though my mom said it was completely normal and it should decrease over time. Please help!