So I had unprotected sex and I ended up taking Plan B that day after.
But now three days later my b/f had sex and the condom broke... so does that mean I am pregnant for sure? Should I take another Plan B? Or is the pill still in my system?

You are not pregnant for sure.

It is possible but unlikely.

You probably still have some of the chemicals from the plan b in your system, so I would not suggest taking it again so soon. You should probably see your doctor very soon and ask his opinion. Also, if you are going to be having sex and don't want a baby, you should look into some other methods of birth control of you have problems with condom usage.