I'm not sure how you got left hanging, but here's a boost.
Camden tablets by themselves are not sufficient for preventing refermentation, especially if backsweetening with the ABV levels as low as yours will be without additional sugar in primary. Add another stabilizer with it before backsweetening. Potassium sorbate and sodium benzoate are popular choices for wine, they work the same for still cider.
Depending on your volume and storage capabilities, you could also cold crash, meaning you store the cider below 40 F, which will cause the yeast to go dormant but not die.