Convertible carseat

Be

Is it time to switch to a convertible carseat?

He weighs probably almost 19LBS now and more than likely 32 inches or more because he had an appointment the 15th of January before he turned 9 months and they said he weighed 18.4lbs and was 23 inches but im pretty sure he has hit a growth spurt since.

He turned 9 months January 21st