I took plan B 3 times. March 4th, April 4th, & April 6th. My last 3 periods were February 23, march 24, & April 18th...now it's march 20th and I still don't have a period..but I have cramps. I have had sex in between April 18 and now. It was protected so I didn't take anything. I have taken 2 first response tests and one Walgreens test and all are negative. I've been feeling naseaus but I think that's because of being so worried! What do you guys think is going on? Is there still a chance I'm pregnant or do you think my cycle is just really messed up from plan B?