Pregnancy hormone level rising but by doubling..

So I went for a scan last Thursday and I was meant to be 5+4 weeks but they couldn’t see anything on the scan. I had been bleeding a little before than and cramping (still experiencing cramping now) They took bloods and asked me to come back Saturday for more to see if levels rose. I phoned up today for my results and they said it had risen but not doubled. Has anyone else experienced this and still gone on to have a healthy pregnancy? 😓 I have another scan Thursday and more bloods.