levels at 414

Okay so I took a pregnancy test yesterday and got a positive, so I went in for a blood draw. They called me today saying the results are positive but they want to to draw my blood again tomorrow to see if they have at least doubled. Should I be concerned? The first day of my last period was May 14 so I would only be like 4 weeks and 4 days along.... this is our first positive since our miscarriage and I'll be devastated if this pregnancy ends the same way my last one did.