Ummm... not sure what else to suggest. As far as grits are concerned you have your bases for a kitchen knife pretty well covered. Maybe a flattening plate and a 240-300 grit, but other than that it looks like you're golden.
What are you looking to do? Is the 1 to 6k progression not getting the edge you want? If not, what kind of edge would you like to achieve? What kind or brand of kitchen knives are you sharpening?
If you are sharpening any kind of quality steel kitchen knives you should be able to get near molecule splitting edges with just the combo stone and strop alone.
Edit: And Mark beat me with a low grit recommendation as well.