No period for 5 months🤷

So I haven't had a period since about November. I did blood tests and an ultrasound and they all came back normal. My doctor has absolutely no idea what's going on so she gave me the pill to jump start my period and told me to call her if after the ten days my period still doesn't start.. well it's day 9 and still no period. She never told me what the next step would be bc I'm pretty sure she was just expecting it to come. Has this happened to anyone else?