Car seats pros and cons

Jenny • I have an angel from December 2013, a baby boy born December 2014 and now tcc for a sister or brother after the sum!!! ♡
Hello, we purchased a car seat that has a base, so we can pull out the car seat and take it with baby inside. I've seen the convertible ones that grow for every stage of their growing life. What car seat do you guys reccomend  and why?