Miscarriage or not? Opinions please!

Kelly • Finally had my rainbow baby in May 2017 after 4 losses! Grateful every single day for this miracle 😍👶🏻
I had my first ultrasound last Thursday  and I was supposed to be 9w5d. Embryo measured 5w. Doctor said that It could be miscalculation or that the embryo stopped growing at 5w. Does anyone know of any stories where the calculation was off for almost 5weeks? Or I shouldn't keep my hopes up because it is most likely a miscarriage? I have another ultrasound this coming Thursday... I am so worried and devastated.