I think the super bulky yarn may be your culprit. The amount of surface area of yarn touching the needle would make the stitches harder to slide, especially on bamboo.
Have you tried knitting with a worsted weight yarn on aluminum needles? I think you'll find that you won't be fighting the yarn. Personally, I like the non-slippery nature of bamboo for double-pointed needles, but for regular knitting, I prefer metal.
Michaels doesn't have the best selection in the world, but some of the acrylics are very soft and nice, and Woolease is a nice blend, readily available.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry