What’s going on

Quenice

So I was recently introduced to birth control I ended up choosing the shot it last for the months then a go back get another I got my first shot August 30th and everything was fine no unnatural changes and as my doctor told me the shot may or may now take away my period the following month sept I had no period then on October 14th my period started my mother told me that it was normal and that me being on birth control would just mean an irregular period but since that point my period has not stopped and I’m still on it today I’ve done as much research as I could but haven’t really found much I’m only 16 and I’m worried it could mean more my mother is skeptical about taking me back to the doctor she’s says it will eventually stop on it’s own after the birth control leaves my system but can anyone offer up an explanation to this