Whoa, wait… how old are you? I thought I was addressing an adult!
Unfortunately, once a child passes the age of about 13, many doctors consider it their personal mission to keep everything about that child secret from the parents! Somehow I doubt you will have a problem with that.
In any case, medical records are private. However, if you use your parent’s medical insurance to pay for the tests, then they may find out about it when they get their statement or explanation of benefits from the office visit.
From what I understand, people go to county clinics and give fake names all the time to get these kinds of tests. That means paying cash or finding someone’s free clinic (if you live in an urban area, they should not be hard to find) so that no one can trace anything.
However, now that I know you are a minor, I can’t stress enough that you should probably talk to your parents about this. I am not going to say anything stupid like “they won’t be mad” but if they are any kind of decent parents, they want the best for you and have your best interests at heart. You need to let them help you.