So I am now 4 days late for my period. All of the pregnancy tests are negative. I normally have 28 day cycles. I got off of my birth control last cycle. I started my period at my normal time. This time I took ovulation tests all month. I didn't get a positive until day 25 and 26 of my cycle. Is this why I haven't started my period? Is it because I ovulated late and I am pregnant or does this happen if you ovulate late even if it didn't end in fertilization? I'm really confused. Thank you.