Hi - my ds is nearly 2.5, 1m tall and weights 33lbs. He is getting very heavy to manoeuvre into his car seat and his feet are against the seat in fron as his legs are so long. I understand booster seats are really from age 4 so don't know if he would be too small for one? Has anyone any experience with swapping over? If I go for it, is there a particular seat anyone can recommend? Thanks