19 days late, spotting

I am never late and now I’m 19 days late, all test are neg, and I’ve been spotting off and on for he last 4 days. Today the light pink spotting turned into bright red and was heavier than before and I also passed a clot or some tissue. But by the evening it has stopped completely. Any advice on what this might be? I thought it was stress because I have been extremely stressed out. I’m planning a wedding and trying to buy a house, could this still be stress related??