Day 41 no period negative tests

My husband and I tried to conceive last month for the first time. My cycles generally range from 29-37 days. I am on day 41 today I have been cramping for almost two weeks and I have been spotting (dark blood) for a few days. I have taken 3 tests over the last week with this morning being the latest test. They are all negative. Has anyone experienced dark spotting and cramping almost everyday during early pregnancy? Could I still be pregnant although the home tests are not detecting it??