T4 i Lenes

Just bought the cannon T4i... with the 18-55 lens kit plus the 55-250 plus I bought the exta 40mm stm... I find myself switching lenes often and It is kind of a pain... Do I really need the 40 or Should I get the kit with the 18-135 stm and the 55-250.. I take pictures of the outdoors plus my little baby boy. I enjoy getting the good blur behind him when taking pictures and was wonding if this would still be doable with the 18-135 and the 55-250. Thanks for all your help.
TJ