TTC since Aug 2009
Disabled queer mama to one preteen, one teenager, 5 cats, 7 chickens, & 1 dog
...granola punk urban homesteaders...
"I found it is the small everyday deeds of ordinary folk that keeps the darkness at bay... small acts of kindness and love."
-Gandalf, The Hobbit
~Manessa mama to one teenageer, one tweenager, and a toddler
Also, this has happened to me before without being pregnant. I chart, so I know exactly when I ovulate and when my period is due every month. One month I was about six days late, but I never had a positive HPT. I have read that a luteal cyst can sometimes stick around for a while and make your period late in the absence of pregnancy.
Dollar Store pregnancy tests are actually pretty good...I would just wait a while and see what happens! There is another possibility...you could have ovulated late and still be pregnant. Maybe it's just earlier than you think, too early to show up on an HPT.