What should I do?

I honestly don’t know what to do...my husband and I have been trying for a baby. However as of lately my cycle gets later and later. It used to be every 28 days on the dot. Now it ranges from 28-46 days. I’m going off of three different apps, Clue, Glow, and Flo. According to them I’m 11-12 days late and my period doesn’t feel like it’s coming at all. I took three pregnancy tests and they’re all negative. Although it did spot for three days (brown blood, sorry if that’s TMI). I’m 21 if that helps and my health is pretty good.