No retina (best) display option I have 2015 early macbook pro 13", but I can't seem to find the 2560x1600 resolution. The highest resolution I can set it on is 1680x1050. Default for display is only 1280x800.
What's the problem here? I'm using the newest Yosemite OS. 

Here's the screenshot:
Apple will not show you the real panel resolution, only the scaled resolutions.

http://www.everymac.com/systems/apple/macbook_pro/macbook-pro-retina-display-faq/macbook-pro-retina-display-hack-to-run-native-resolution.html

Try this.