AT 8.5 wk the fetus is very small,
the dark spot on either side of heart on one image-
---- this not correct medical terminology to be used in ultrasound
, better would be hypoechoic / anechoic- may be doctor has interpreted to you for your better understanding
Its quite possible that its just an artifact
the advice to repeat ultrasound after 2 wks- is important as by than fetus will grow and become large to comment on these findings with certainty.