I know its scary, but the absolute best thing for you to do is to tell your parents. I know they will be disappointed, but honestly things will be much easier with them helping you to find out if your pregnant or not. They can get a pregnancy test for you, and it will be much easier. I think telling them you may be pregnant and finding out together is much easier than finding out after the fact. At least they will be able to see that you felt like you could come to them.
I will tell you that I did wait till my wedding day. No it wasnt easy, but we really are best friends and we know each other so well now because of it. I know you probably dont want to hear this, and it would be super hard because you already had sex, but any man that really loves you will see that you are a jewel worth waiting for!! Dont sell yourself short because waiting until your wedding night is amazing and sooooo much better. I had sex when I was 16 and thought I was pregnant. I was so scared, and ashamed that I could be so young and get pregnant. I resented myself for it. When I waited for my husband on out wedding day it was so much different. I can only tell you from being able to look back now and say that I wouldnt change that for the world, it was the best thing we ever did! Our marriage is so secure because of it. And I knew that my husband waiting for me and not pressuring me meant that he respected me and my body, and because of this, I know that he will continue to respect me and that if he had self control when he loved me that much to not have sex, that he wont have sex with anyone else but me still. You have no idea how amazing that feels!!