Is the seat still backward or facing forward? I would turn it around faceward and see if that helpsshe can see out the same direction as the car is going.....
The bub is only 3 months old, it is illegal and unsafe to turn the car seat around at this age.

My DD also hated the car when she was younger, i also live country and so most of my drives are longer ones. I knew all the safe pull over points between here and Melbourne too well! A mirror for bub to look into (and see the driver) helped a little. definitely worth trying if you don't have one. Is the sun in bub's eyes?

good luck