Pregnant or not? What should I do?

AF is 9 days late, was due 1/14 but have had no signs of AF or of pregnancy. My cycle is consistent every month. I've taken 3 tests and they have all been negative. Should I see a doctor? I'm 19 and in my first year of college. If I went to the doctor, I wouldn't want to tell my parents about it (they can be pretty strict and don't want to scare them if I'm really not pregnant), I want to be 100% sure I'm pregnant before I tell them anything. Is there a way I can see a doctor without them knowing? Is the bill for a blood test expensive? Still new to the whole ttc thing, so I'm not sure how this all works! Any advice would be appreciated.