my reading from my ro is 15 and di is 3. Although it would be nice to be 0.
I only got 0 right after a new di change. I seem to be going through di a little faster, it seems to settle at 3.

When I first run the water through it does have a higher reading and settles on 3.

How long do you run it before testing? Your reading before ro and di is in the teens, thats ok.
It would be nice to be lower. DI should handle the rest. How new is new on the DI?
If its not sealed correctly (when storing) the DI can go bad, i think. just an fyi