My sis is 16 months older than me. Speaking about little time apart. Lol. And I can only say that it must have been so extremely tiring for my mom. Our father was most of the time working, his day job, and in the evenings odd jobs for extra money. Mom was at home for us, and having two girls just 16 months apart has sure not been easy for her. What I remember is that we could get in girl fights like cats and dogs, but also that we were very close friends when we grew up. She was always there to protect me. And later we had often the same friends to hang out with in the weekend.
Enjoy every precious moment, those are the moments that will be in your memories forever. You're blessed with such a cute boy who really wants to take care of his baby sister. Bless them both!