Where are the missing speeds in my KitchenAid mixer
This is mentioned in the user manual for your stand mixer (the larger more detailed booklet, not the quick start pamphlet). 

Those speeds exist on your machine, they just aren't labeled. The odd speeds aren't commonly used, so by design the lever is predisposed to "notch" at the evens, and the lever naturally wants to find a place there. However if you need more granular control of your machine, you can adjust the lever to stop in between speeds.  For instance, if you want to set to speed five you would adjust the lever to speed four, and then carefully move the lever forward until it sits between four and six-- that is speed five, and the lever will stay without snapping either forward to speed six or backward to speed four.