7Kg of Dextrose in an assumed tot volume wash of 25lt would have given you a SG of 1.107 and with a current reading of 1.005 the alcohol content of the wash would be in the region of 13.15%ABV which, if you're using one of those yucky Turbo thingys, is still a bit low.
Your potential is somewhere around 16.5% which will be indicated by a gravity reading below 0.980. More likely this one will end up, based on your description, at around 0.995 or 14.5%.
Generally, a few bubbles only every 30 minutes, or so, is indication that the yeast is not producing very much any more. You could try a kick start with some nutrients but you got to ask yourself will what you 'might' gain be worth the cost or the effort.
Many things can stop a wash going all the way, Ph, initial O
2 to feed the Lag phase, temperature swings between day and night, etc. I doubt any of us get it perfect all the time (or ever) but 14.5% is a reasonable result provided it's not sweet.
Next time try substituting just 30% Dex in the total sugar weight.
Good luck with it
AM
