T.D.
I invested in one of each kind and tried them all. Then the ones that didn't work, I kept one of each to use on my second child, and eventually passed all of them onto two other moms to do the same.
I just tried each one and kept the one the baby kept in her mouth the longest. To get the baby to take it took some persistence on my part. Keep offering it and nurse only to feed.
Best wishes.