What’s going on? Help!!

Heyyyy so I made a dumb decision of having unprotected sex on the 26th of June. He pulled out but there’s this thing called a precum idk if that happened so I got very anxious thinking I’ll get pregnant. I took a plan B but lately I’ve been lightheaded, bloated, cramps, fatigued, had a really bad headache. My period starts hopefully in 4 days. But I just have a huge fear of being pregnant. I also took a test this morning and it was negative as well. Can someone please explain to me what’s going???