Missed period


I need some advice or help. I’ve missed my period for 9 days now. I’ve got pregnancy symptoms like sickness but only occurs at night. Breast soreness. Back hurts, constantly tired and so on. But I have lots of discharge first thing in the morning which is milky.. never experienced this before.. tests all say negative so a bit lost on what to do if I’m honest? I’m 17 years old. Never missed a period before so? Help needed ASAP