How to know I am ready for a baby?

Hi, I am 18, living with a partner, got a house and pets. I am feeling broody lately, how can I determine whether I am ready? I worked out we would have about �200-300 spare a month when I'm on maternity leave, plus savings for the baby items. People keep saying I'm not mature enough, im being selfish etc etc but I do truly feel ready. Advice anyone?