Period late 1 day but 2 negative at home preg tests?

My husband and i are ttc#2. We have tracked my cycle for 3 months and started taking fertile aid as well. My period was due yesterday and its always pretty much on time. I took a preg test last week and it was negative and then i took another today and it was negative again. I know i have been pretty calm so i don't think it could be stress or anticipation. Anybody have some advice or suggestions?