It's OK that you're nervous. What you need to do is communicate with your boyfriend, that way he knows what's going on in your relationship. Nothing good comes out of hiding things. It only makes things harder on you, for sure.
About the pregnancy test. You can go to Planned Parenthood to get an (i believe) free pregnancy test. They do a LOT of stuff for teens in your position.
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Im a front porch sittin, guitar pickin, moonshine sippin,
baccer chew spittin, COUNTRY BOY FROM THE WOODS.