Non-diabetics go round with figures like that all the time. As a Type 2, if your levels are too low, your liver will dump sugar into your system.
It is only people on insulin and meds like Gliclazide who need to worry if their levels go under 4.0 mmol as they are at risk of a hypo.
The low carbing is definitely working for you - keep up the good work, it is giving your poor overworked pre-diagnosis pancreas a rest.