Hey, d00d. I'm not too much older than you, so let me tell you about my scare. I had been seeing (exclusively) this certain girl for a few years. We had been thinking (and still do think) that we have a possible future together = marriage.
Well, it seems that her cycle was a bit late one month. Nothing to worry about, right? We'll wait it out. Day after day...nothing...Nothing...NOTHING. After two weeks we were pretty much convinced that she was pregnant. We cried together in her room. My whole life flashed before my eyes. We weren't ready to be parents, and an abortion was out of the question. She was in college...I was in college...what am I going to tell my parents...how will I face HER parents...they like me so much...there's so much I wanted to do with my life before kids...and so on...
I tell you...I was absolutely SICK. You, my friend, do not EVER want to feel like I did those few days. When your woman announces that she's pregnant, it should be a happy occasion for all involved. It shouldn't be a cross to bear as you sorrily inform your/her parents of your misdeed. I was almost ready to bite the bullet and take her to the doctor for confirmation...when her 'visitor' FINALLY showed up. OVER TWO WEEKS LATE!! My life was handed back to me - and I vowed to never again put us in that position.
Since that scare, we've decided to avoid sex until marriage (aw, hell...maybe engagement...how much can a guy take?!), and we've kept our promise intact. Two years later and we're still going strong!! It's not a hard promise to keep because I remind myself of our situation...we're broke and can't afford kids.
My advice is to wait to do the deed. Get your life in order first, and have fun while you finish growing up. Don't rush things - they won't turn out right.