the pull out method is not 100% effective. if one of those little guys get in side you, that's all is needed.
on the other hand you could have this all in your mind. i remember i had pregnancy symptoms just like you and i was fine.
cross your finger and take a test in two weeks. and get on the pill so you dont have to go through this again.
using the pull out method is one thing, using it when your ovulating is another.