Plan B Questions!

Aesteria
So, this is my first time taking an emergency contraceptive. How this came about was that my boyfriend lost his hard on and we decided to end it there. I was straddling him at the time and when I lifted myself up, I took the condom with me. I started to panic and took the condom out. Precum spilled on top of him. My boyfriend reassured me that the condom was not in all the way in and that nothing had spilled inside me. To take extra safety measures, we went to get Plan B and a pregnancy test to be sure I wasn't pregnant from the times before when we've had sex. The test came back negative. 
My question is, is it normal to not have any symptoms from Plan B? I felt a bit tired when he dropped me back off at college, but nothing else. I felt a few light cramps just now, but I still don't know?