Having trouble getting baby to take a bottle?

My baby is 6 weeks, and I am back at work only a few hours a week. We have tried almost every bottle nipple available, and they are either too hard, or too long and he gags on them. He has also never taken a pacifier. He seems to have a very strong gag reflex. Anyone have any ideas?? We've tried Avent, playtex naturalatch, gerber orthodontic and the johnson's healthflow ( the short, wide ones) the johnsons he seemed to take the best, but gets a lot of air. My sis said he takes the gerber orthodontic ones into his mouth really well, but ends up gaging on them. Any help is appreciated!