Late period. Help!?

So here is the background to my story. My husband and I are TTC. I woke up on cycle day 17 with pink spotting, cycle day 18 brown spotting, cycle day 19 red spotting, cycle day 20 with pink spotting again that stopped that evening. I am now on cycle day 38 with no sign of a period. So 8 days after my expected period. I have taken three tests now and all are negative. One 3 days before expected period, one 3 days after expected period, and one yesterday. Could I be pregnant and the tests just still be negative? Or has the mid cycle bleeding just caused my period to be late.