Hi L.,
Of course I can't say whether you are pregnant or not, but I do see two things that can make your period late. First of all, it sounds like you are under a lot of stress! The stress alone about your husband being laid off can be enough to make your period late. I actually have a few friends who can become late with their periods if they get stressed out. (And they also think they are pregnant each time it happens, but so far, they have been false alarms!)
Also, the exericse program you have started can also cause your period to be late. Even if you started out slowly, this can be a big adjustment for your body to make, and this can definitely cause you to be late.
I would recommend waiting one more week and then take another pregnancy test. If you still do not have your period by then (and the test still comes out negative), you can always call your doctor.
I wish you luck and hope everything turns out the way you want it to! Try not to worry!! (Easier said than done, I know...)