Beta HCG question...

Sarah
So I had my blood levels tested at 5 weeks 6 days and again at 6 weeks 1 day, they just over tripled which I was told every 72 hours they double, and it was less than 72 hours in between! Could that mean I am having twins?! At 5.6 they were 2,239 and at 6.1 they were 6,777! No ultrasound yet :( I have to wait till December 15th 😭