Negative Blood Test!!!

Alonna • My wife and I are trying for our 3rd child, our 1st together! I will be the one getting pregnant, we have found a donor! Hoping all goes well and we end up pregnant our first try!!
We did at home insemination, with donor sperm on 10/29/15. Went to the emergency room last night, they took a mandatory blood pregnancy test. It was negative. My period isn't suppose to start till next Friday. Is there anyway it could be wrong since its only 7 days after trying??