hcg levels rising but not doubling

Cr
With my history everything paranoys me. I've been bleeding since my trans vaginal ultrasound yesterday. I can to the er to Check my beta levels. I'm 6 weeks 4 days and my levels 2 days ago were 4496 and now they are 5272. So going up but not doubling. 
Anyone have positive stories about their levels not doubling but having a healthy pregnancy?