aawwwww, try and give yourself a break honey. You went this long without a dummy, you should be proud of yourself. They do say that dummy's can affect their sucking etc etc when breastfeeding. But my personal opinion, I think it's ok. Nina had one from about day 3, and she never had problems. I wish Emily would take one at times too. If he is hungry, he will not suck on that dummy, he will continue to scream until he gets fed. If he's happy to suck on it, and is content, then let him be. He might just be a baby who needs to suck.
Just remember you're doing a great job, and the best job you can possibly do. Don't put too much pressure on yourself.