Raine says that Laguna spent six months just recovering from his injuries.

Doesn't Kiros say he's been looking for Laguna for an entire year, too?

Kiros and Ward had quit the army, and Ward had changed to a completely different job. Those kinds of changes take a while.

Clearly, the better part of a year or more has passed between Laguna's friendly chat with Julia and his meeting with Raine.

Besides, Julia didn't even meet Caraway until she was absolutely certain that Laguna wasn't coming back. She was distraught, he consoled her, they eventually fell in love. Those things also take time. Caraway might;ve noticed if she was pregnant.
It's not like Julia just got bored and started playing around simply because Laguna had been gone for a few weeks.