If the bottles have a funky shape, you might want to try and give them the same amount of headspace when filling them. My bottle wand displaces just the right amount of volume when filling the normal 12-oz brown bottles, so I just fill to the top of the bottle, remove the wand, and I'm fine. If you normally do the same for the smaller bottles, you might want to tweak the process accordingly for the larger bottles (if needed).