Premature baby question

Tell me if I have this right? Baby is 3 months premature

Adjusted age just means the developmental age that the baby is at?

Let's say a premature baby is now a year old, but his adjusted age is 9 months.

He wouldn't developmentally be one for another 3 months?

Because technically if he was born on his due date full term, from the time of conception to where he is now, he would only actually be 9 months old.

So he's not really even a year old until he is 15 months old