On YAZ are you supposed to have a period?

I thought that on YAZ you are only supposed to have a menstrual period every three months. But I was speaking with another friend of mine who is on it as well and she said she read in the books that your supposed to have a period every month they are just supposed to be light. But my doctor said I would only have on every 3 months. But I'm starting to worry cause maybe they got some information wrong. My friends pills look the same exact way mine do and they are in the same pack and everything. Are there different types of yaz? Or am I really supposed to be having periods? Cause this is the 3rd one I have missed.