IDAC is not the only thing which has the effect on the counts. The prescalar that is analog switch divider for the switching clock also changes the count. If counts are saturated for all the values IDAC then change the prescalar value to bring the counts down to middle of the range then start playing with IDAC current.
Here is the controls of your CapSense counts:
1) Increase the IDAC current -> The counts will decrease and vice versa
2) Increase the switch divider value so that switching freq decreased -> The counts will decrease and vice versa
In your case counts are too high that they are saturated so bring it down by decreasing the prescalar or (switch divider value).