What could be wrong?

Before waiting to see a doctor i need some opinions from you guys maybe some of you are in the same position as me, i got my IUD removed last week of February I have been getting my period month by month sometimes it doesnt last a whole week only about 3-4 days, this month my period was due on the 18th im 3 days late i took a pregnancy test on the morning of the 19th and it was negative .. could i have ovulated late? Maybe stress? If i dont get my period by the 30th i will be taking another pregnancy test and if it’s negative ill be seeing a doctor. We have been trying for baby #3 for 6 months and no luck my last pregnancy after coming out of my IUD it took 8 months for us to conceive 🤞🏼 what are your thoughts?