Any one else experience this?

So we're happy to find out we're pregnant... Going by all apps it was saying that we were 7 weeks pregnant... Made the first prenatal appointment and were actually around 4 weeks pregnant. So now the doctor took blood yesterday said return Friday (tomorrow for another blood work), to ensure the pregnancy is going as needed and will not end up in a miscarriage. No signs of miscarriage no blood paid ect. Is this normal procedure? Has anyone else been through this?