Ultrasound scan confusion

Abi • 22- Mommy to baby Hugo 06.03.19👶🏻💙

So I went for a follow up scan today as there was a some concerns at my last scan 2 weeks ago. At my scan 2 weeks ago the fetal pole was measuring 3.8mm and there was a heartbeat present. At scan today the baby was measuring 6.2mm so had obvious growth but technician said there was a ‘slow’ flicker of a heartbeat so booked me for another rescan in a weeks time to see if it’s going to be a viable pregnancy or not.

Has anyone else had this and everything has been fine with baby?

So worried now as had a miscarriage already back in November 😩