My boyfriend has a big penis but I'm scared it won't fit inside me!

Your vagina is incredibly stretchy, remember it is design to allow a baby to come through it. Just be sure that you are very sexuallly aroused before you attempt intercouse and he uses plenty of lubricant. Also take your time when having insert himself into you, insert just the head of his penis and remove then each time have him push a little further inside. Once he is in, keep still and get use to the sensation before you start thrusting in and out.