Something that might help is this. If you wait to long to let go/throw the disc, it loses potential distance. That is, if you let go of a disc at the end of your out stretched arm, you are not harnessing the maximum potential of disc flight. Releasing the disc between the distance of a curled arm/or one close to the body and an out stretched arm will have a greater force applied to the disc. This should help you stand and throw, or even rock back and forth and throw rather than having to walk into a putt to get a greater flight path. The more variables you have in a putting stroke, the more that can go wrong and will throw off your timing, which is the bigest thing with putting. Work on timing the release of the disc before you come close to stretching out your hand. Play with it and find a happy medium. If you can come across some video of Walter Haney putting, it looks like he just shoots the disc right out of his chest.
If you look in the throw analysis under Larry Leonard you can see that his arm is just past 90 degrees when he is releasing the disc.