Have you tried using the ink analysis in the job dialog?  Open the job log, select a range of jobs, and then right click in that range and select "Paper/Ink Analysis".

Like counting prints, it'll give you a count of the area that has been printed in a certain range of (for example) dates.  I don't "plug" the feature often because it has limited use.  It only gives you the amount of area printed in Qimage.  It can't account for ink usage in other software, cleaning cycles, etc.  Looking at ink area or print count also can't tell you how much of each ink was used.  You might have printed a lot of photos with blue sky this past month while the month before that you printed a lot of green foliage.

It does, however, give you an idea of how many prints of a certain size you could print between two dates, for example between the date of the prior refill and the current one.  As an example, an 8x10 has an area of 80 square inches.  If you find out that a certain range of jobs used 2000 square inches of area, that would be equivalent to 2000 / 80 = 25 8x10 prints.

Regards,
Mike