Most (all?) Phyllostachys bamboos are sun-loving and need a lot of sun to thrive, so that may be the problem. Bamboo is also a heavy feeder, so maybe you do need to fertilize more (you didn't give details on fertilization). Mulch with compost and other organics too.

Do you also understand that individual bamboo culms do not get bigger from year to year? When a culm comes up it reaches its final height in about 2 months and never gets any larger. In addition, you have less than ideal growing conditions and temperatures. In fact, your bamboo is only supposed to be hardy to about 0 degrees F, so that fact that it has not died completely means you are doing something right. I don't know what to tell you other than to try some other bamboo that is hardier in your growing Zone, like Ph. nuda or one of the hardier Fargesias.

Ph. nuda wouldn't be a great choice if the "lot of wind" that they get is when it's cold. Cold, dry wind is the worst for bamboo, and nuda isn't as wind-tolerant as others from what I hear. Some winter wind protection while the plant is young may be in order -- wrap it in plastic for instance.

alan-
I don't know if nuda is less wind-tolerant than other species. I think the conditions described will be bad for any foliage, so I focused on species that would be able to handle low temps best. In any case, it's a craps shoot...

Shade should not be a problem but as far as it goes bamboo does not like wind very much. This will make it harder for your planting to persist through cold winters in a climate that is already of questionable suitability. Even the most hardy, high altitude bamboos (this is not one of them) are native only to moist climates, typically downright wet during the growing season. Low humidity, and perhaps as well as mineral salts in your irrigation water could both be problematic.