Could I have gotten pregnant the day my period was due?

10 years ago I had a tubal ligation done. Then 2 months ago I had my appendix taken out. 2 days after my surgery my period started and exactly 28 days later it started again. The day my period was due, June 5, my husband and I had unprotected sex and I have not gotten my period yet. I've taken 2 dollar store home pregnancy tests, one at one week late, and one yesterday using the first morning urine. Both have come back negative. Could I be pregnant?