PMS symptoms but no period after Plan B

We ran to the store and got Plan B, and I took it about an hour after sex. A week later, I started having the same symptoms I get on my period, like nausea and bloating, but they were way less than normal. The second day of having symptoms I took a pregnancy test, and it came out negative. I don't know if it was too soon to take it, because my period is irregular and can come anywhere from the 13-30th of the month. I felt symptoms on the 20th and took the test on the 21st. It's been 4 days and my period still hasn't come. I know Plan B can delay your period, but online I also read that it's the first sign of pregnancy. Could I please have some advice on how long I should wait to take another test and does anybody know my chances of pregnancy?