Late w/ 4 BFNs

TTC #2 for about two years.
I'm 5-7 days late (I'm not always on time), and I've had four negative home tests. I had PMS symptoms for a couple days, but nothing. I really don't want to keep wasting money on pregnancy tests, and I don't have time to go to doc right now. I hate not knowing.
What do you ladies recommend?