Doona x newborn head support

[noveltybobble]

Hiya
Has anyone else got the Doona X and has used the newborn insert? We tried it in the car today for our 3 week old, and the newborn insert makes the headrest basically flat so there’s no side support to stop his head flopping to the side. I’m just wondering if I am missing something!?
Also the seat is really upright in the car, so without any support around his head he could easily have his head fall forwards. The newborn inserts for the older Doona’s are a totally different shape; they fold around the head.
Don't understand!

Do you have quite sloped seats in your car? Are you fitting it with the base, or with the seatbelt?

I’m not sure if they’re more sloped than normal it’s just a VW Polo but they are definitely sloped. We are using the isofix base. Thank you for replying!