I've taken 2 negative pregnancy tests but still think I'm pregnant?

My period is about 5 days late. I've been so exhausted lately, getting bad headaches, frequently urinating, having upper back pain, my teeth are aching and ive been having slight cramping. Ive already taken 2 tests and they've both been negative. I had unprotected sex quite a few times this month (my husband and i are trying for a baby). I don't want to get my hopes up more, I know the tests are negative, but could I still somehow be pregnant?