Finally pregnant

Had a normal 5 day period and 2 days later found out I was pregnant!! Was unable to see the baby on an ultrasound at the ER because I was too early, but my HGC levels are raising so no more cause for concern. This will be my third child and this never happened to me before. I’m currently 6 weeks pregnant and will be having my first OB appointment and ultrasound at the end of this month. Has anyone else ever had their period and ended up pregnant the entire time?