FINALLY :)

After doing this 5-6 times and thought the achievement is glitched .. I finally got it & i want to share it with others like me who had the exact same issue with me "i did everything but the achievement doesn't pop up"
I am gonna tell you almost every move i did even though it might not be nessasary BUT it's worth to try it and finally get the achievement.

1. Play as Jill on Normal in "once again..." mode.
2. Save both Chris (obviously) and Barry.
3. You can use extra weapons like infinite launcher .. it will not effect the achievement.
4. Read all the files.
5. Take all the maps.
6. Pick up all items.
7. Check every room and place to be green.
8. Use all kerozine.
9. Visit all the rooms even if they don't have anything to pick up inside.
10. Unlock all doors and pass through them.
11.Don't forget the shotgun shells inside the cell when you save Chris.
12. OK here is the one thing we all been missing and was ruining our lives LOL
It's propably this one :
The locked doors that you can not open .. you should try to open them and then check your map to see if there's a X on the red sign where the door stands.
No12 is the only thing i was not doing right every time .. i was checking and mark as X not all of the locked doors.

OK .. i hope this will solve your problem :)