How do I unclog a slow draining shower?

It is a stand up shower, not a tub. We have only been moved in for 2 weeks. I know it is not my hair because I have used 2 different drain snakes (one of them being 8 feet long) that did not pull out anything. I have also tried Liquid Plumber and Draino and neither of those has worked. The shower drains so slow and I can barely even rinse the soap off of me before I have to turn it off before it overflows. Please help me!