Okay... Update... Is this right?

So, long story short. Took Plan B on the 7th last month and bled 4/5 days later for 5 days. Ovulated on the 18th and messed up, had successful withdrawal method that night but was still scared after my period has been 4 days late. I took a pregnancy test yesterday, 2 weeks after ovulation for sure, and it came back negative. Is that a for sure negative? I've had weird symptoms like my period is coming and it just hasn't yet. I know Plan B can mess with your cycle too. Any advice? The test was a strong negative.