Well both 22x22 and 32x32 would be good. If some icon are missing in one size it will go to the next folder. So you do not need all folders but they could look blurry if the resizing was too big. The easiest way would be to use an already existing icon theme. Download one from your phone to your computer. Preferable the "/usr/share/icons/hicolor/" one. Then swap the icons from anna-icon-pack to hicolor, one by one, so that they get the correct name. After it is just to rename the hicolor folder to anna-icon-pack and move back to your phone and put it in "/usr/share/icons/".