I have 4 packs of props that cam with my Y6 kit (purchased from Unmanned Tech). 2 were 10X50's and 2 were 11X50's. However, I'm kind of sure that the top 3 clockwise motors need the 'R' pusher prop but I only have one per pack( 2 in total) The same is the case of the larger props for the bottom motors, but I think require the non pusher props.

It does seem that some props are possibly missing form your kit as you should of received 3 pairs of each. If you could double check the packaging (although props are not exactly something small that can be missed!) and if you cant find them, please send an email to support with your order number and I will get some more props sent to you.