Since you are not using standard FileMaker checkboxes, you'll need to describe your method in much more detail so we can see how it works.
ToggleField appears to store a 1 if the checkbox is selected and 0 or blank if it is not.
You can define summary fields that either count or total togglefield to produce a count of the number of selected check boxes. Which you use depends in the exact values being entered into togglefield when it is clicked to select or clear the checkbox.
If the values are either 1 or 0 in all cases, use Sum. If they are Nonzero or blank, use count.