Thinking about ttc

Okay so I need some advice I need help! So until I found my fiancé I NEVER wanted a baby of my own (I was a step mom to a 6 months old for over 2 years) I’m almost 19 (I know young) however I’ve had to grow up very fast due to my mother having cancer when I was 10 until she passed away Jan 18, 2018 she was very weak during the 8 years so I had to step up and help be a mom to my little sister cleaning the house cooking cleaning getting her up for school and all while taking my mom to doctors appointments 6 hours away when I turned 16 and was able to drive. But my mom wanted me to have a baby before she passed and Feb 28, 2019 my papaw passed away who stepped in as my father figure when my bio dad passed when I was one. But I’m dying to have a baby of my own but my fiancé wants to wait but it’s killing me because I’ve had so much depression since they’ve passed and I’m ready to be a mom I really am but how do I open his eyes to have a baby???