as pre-ejaculate can contain sperm, you might want to take the morning-after pill just to be on the safe side. I don't think it will do you any harm to take it. You sound pretty clued-up, but have you thought about going on the pill?
Otherwise, welcome to bust. Normally we don't like to start new threads - you might get more help in "do i need the morning-after pill"
over in the let's talk about sex forum. Hope that helps and you get sorted!