Pete Davidson and Elsie Hewitt are already talking next steps after welcoming their baby last month ...  and yeah, marriage is very quietly hovering in the background!

Speaking to Us Weekly, Pete said they do talk about the future -- “I think, obviously, we talk about next steps and all that stuff" -- but right now they’re fully in survival mode with 1-month-old daughter Scottie ... focused on locking in a routine and, in his words, "keeping her alive."

What is on their minds? More kids. The couple says they definitely want Scottie to be a big sister, with Elsie admitting she’s already had the "I want to do it again" feeling.

That said, she also confessed thinking about another baby right now sounds "absolutely insane," especially after how intense the whole birth experience was.

Bottom line ... they’re deep in family mode already, and between more babies and possible wedding bells, this new chapter is just getting started!