if you are not confident about the waterbirth this time, that in itself can slow things down
Michel Odent , who pioneered water birth, recommends getting in the pool at 5 cm , not before, so you didn't get in too early
however, as happened to you , you can get too relaxed! but, the urge to push does not always come the minute you get to full dilation.
Shivering is often a sign of transition, but can be followed by 'rest and be thankful', a pause in labour before you get the urge to push which allows you to get some energy back. Some hospitals are not terribly comfortable with this , hence you got given syntocinon...and all the subsequent interventions..
have you thought about a homebirth, and then you can labour on your own terms, use the bath for pain relief early on, or hire a birth pool..
that way, even if you have another pause in your labour you won;t get the whole thing of synto/epi etc...