It probably shows best in your pic 1. From the eyebrow to the top of the fore head/start of the hairline area, to me, looks flat and slightly sloping back. If you look at the pics in post 1 the boy shot has the same gentle flat slope back, where as the girl shot has a curved hill between these areas itms!
A scan at 13 weeks will definitely give you some perfect shots to look from, plus the private machine would probably be of a better grade with the pictures being less grainy:agree: Also if you get a scan at 13 weeks then you can still officially stay team yellow if thats your hope as it still not 100% official;)