I Just got a new paddle, i made it about 4cm longer than my old one as recommended , the shaft seams to have about the same amout of flex but the blade is bigger than my old blade. What the verdict. Which is hurting my shoulder, the bigger blade,longer paddle or stiffer blade.Any opions would be great, Thanks

Try the old paddle again and see how you pull up.
Both a bigger blade and to high a shaft overhead can put more stress on the shoulder,so you've got a couple of things to work through there,
Cheers,
Camo.

I like it about eye level.. (when I push forward).. for flat water.. Maybe it's around chin level for my surf paddle.

You should check your paddling technique.. There are two ways to swing the paddle blade out and forward to start each stroke.

A lot of people just drop their top hand and swing their lower arm straight forward.. This causes a big looping motion of the upper arm. and a big rotation of the upper arm shoulder socket.. Having your upper elbow cocked out slightly is also bad.

I think it's best to swing the lower arm out and forward and keep the upper hand just moving up and down in front of your face while keeping your top elbow down.

I remember once hearing Dave Chun from Kialoa paddles saying that your upper hand should just move up and down in front of you and I checked what I was doing and it was nothing like it... It is now.

I find that when I'm getting tired and loosing form I start going back to the dropping/relaxing the upper arm with that big rotating motion and I think that's ok to do it some time.. but not all the time.

That's my two cents worth.

DJ