I wonder what your surgeon thinks about your situation? Isn't he in the best position to advise you?
Nonetheless, when you hear hoof beats behind you, please don't immediately think "zebras". Stated differently, the simplest explanation for a situation is often the correct explanation.
If you are only seeing 2 mm of distraction; then, the simplest answer may be that you only distracted 2 mm.
It would be challenging to accept that you distracted 10mm but had the most miraculous healing in the world so that it looks like you only distracted 2 mm.
Bone simply does not heal like that. I encourage you to read some journal articles that explain the biological course of healing for broken bones. Once you do, you will likely agree that you are not pre-consolidated.
What's more, so long as the top of your fibula is captured by at least one screw; then, pre-consolidation is nearly impossible with external lengthening. This is so because when you distract, you will merely pull apart your bones at the osteotomy site because the site is the weakest part. (If your fibula is not captured; then, the cartilage at the top of your fibula can be the weakest point; thus, a risk of pulling that cartilage exists.)
While I encourage you to discuss your project with your surgeon and to take your guidance from him, two possibilities come to mind to explore. First, it is not uncommon to turn nuts in the wrong direction so that you cancel out turns in the correct direction. Some folks wrap tape around the rod just below the nut to help ensure you become used to turning the nut away from the tape.
Next, it is also possible that you merely "took up slack" in your first week of distraction; thus, you will see more normal distraction next week.
All-in-all, it is probably too soon to sort things out definitively. I encourage you to talk with your surgeon. This is a new experience for you. It is likely NOT a new experience for your surgeon.