Has anyone ever experienced this

Has anyone ever gotten their period and then ended up being pregnant? I had what seemed like a regular period but it only lasted 4 days. That was about a week ago and then yesterday morning I woke up and just decided to take a test idk why but when I did there was the faintest blue line and through out the day it only got darker. I don’t really know what to think I’m gonna take another one in the morning and if it’s positive I’m going to get a blood test