Stay rear facing
The aap recently recommended that babies remain rear facing until at least 2 yrs, or later if under the maximum weight for that seat.
Car seats with "side impact protection" are being marketed but there is not yet standard testing for this feature. If possible, the middle of the back seat is safest. Booster seats are for after 4 yrs or 40# (whichever later), but many car seats accommodate 100#.