So he's in the future of the past he went to! Also my first thought on seeing all those pictures was not that someone had been sending them to him for a long time, but that he drew them himself in this timeline... but I guess that's not true since he apparently jumped forward 15~ years.
Hey... Bungo didn't mention anything about a third child. What if the pregnant woman depicted in the drawing was Bungo's wife, Shin's mum, who was pregnant with Shin in this timeline?