my 4 year old (5 in October) spends a couple days a week with his grandmother (his dads mother) so I can work, because his father has mental health issues and so he doesn’t get to keep my son for the time being until he’s doing better mentally. His grandmother bought my son a booster seat and the seat says you can start using it at 40 pounds and he’s 44 lbs but I feel like he’s still too young to use it. I just feel like it’s not safe enough yet. Am I wrong? Or should I not worry