Might be prego URGENT

I had a 31 day long period in april from the 11. On may long weekend I had unprotected sex with My bf and not even a week or 2 after he came inside me I started feeling nauseous I couldn't eat anything without the feeling of throwing up and I had a light blood flow it was kinda pink red and rusty brown colour didn't really stay one colour. I took a test and it said negative but I'm really confused.