Just one kid

While i read lot of lovely posts about second child or Another kid after oct 16 one.. i wonder how many mamas are like me .. havign just one kid so far and feels like he takes all my energy .. i want to have second kid but dont know when.. anyone else in my boat ..?? Just wanted to know if it will be too late to have second kid ?? I was thinking to have gap of 4 yrs but these updates of second kid keeps me busy abt thinking to have my second .. but the. First one exhaust me :/ confused and lost