Hcg levels

Hayley • Engaged to the man of my dreams 4 years ttc mmc angel at 2 year mark bfp 13th feb baby #1 due oct 2015
Is it true your levels stop doubling after 6-8 weeks ? My hcg only went up 800 in two days but I'm in high 80s was just curious and scared freaking out about my scan on the 30 th now 😥 I thought with all the early scans it would help but it's made it worse I'm terrified to go in 
Was going to but a Doppler for reassurance in general but now I'm at a cross dd of not wanting to waste money just incase 
It's so hard this being preg business