hi punk princess!!
my advice to you would be to relax!! maybe if you are worrying about it hurting then you are tensing up and this would make it damn near impossible for your boyf to get in!!
dont rush the foreplay, the more turned on you get the more lubricated you will be!! during foreplay have your boyf go down on you, or have him put one finger inside you and when thats comfortable add another, and when thats comfortable add athird!! if you can take three of his fingers with no pain you should be able to take him!! i woud say the key probably is to keep masturbating and using bigger objects till you can comfortably accomodate them!!
if all else fails then yeah, go see your doctor but i think if oyu just relax, take your time and dont rush anything it will all be ok!!