Good day. The question is off-topic. My period always comes on the sam…

Good day. The question is off-topic. My period always comes on the same day every month. Straight as clockwork. After childbirth, they started two months later, and immediately like before pregnancy. No deviations. Now there's a delay for three days. But I exclude pregnancy (not 100% sure). We've been together for 10 years. Something similar hasn't happened. Pregnancy was planned. Could anyone have a delay for other reasons? It's not possible to see a gynecologist in the next two weeks. How soon can I go to her? If there's a delay, when can you take a test to show it clearly. In my first pregnancy, I didn't do