Originally Posted by
Ruff
There's no genetic predisposition for water shyness so it isn't inherent. If she is water shy (Which I highly doubt) it will have been caused by a traumatic event which you will be aware of. It sounds like she's a typical happy puppy at six months lacking a bit of confidence which she will gain as she gets older. As the others have suggested wait till it warms up a bit and in introduce her deliberately and without pressure to water. the very best way is with another dog or dogs which are water confident. Start with things as simple as water logged paddocks/swampy ground where she can splash around with the other dogs and slowly lead her to deeper spots where she will follow the other dogs and swim. She'll get it no worries but don;t even worry about it yet.
And five minutes is way too long to be doing retrieves with any dog. Do one or two well and stop. It'll build her desire for more. Bore her with it and she'll prioritize other things.