Custom Module - Creating report and chart to display totals against target

Custom Module - Creating report and chart to display totals against target

I have created a custom module (trying to do this in custom module rather than Creator) for the sales team to log monthly data for sending some invitations to events we run.  It's not a complicated form, but I am unable to create a chart from a report that displays how each sales person is getting on with their monthly targets for each metric.
  1. At the start of the month each sales person will create a new record, enter their working days that month (the tool will then calculate their targets for each of the two metrics).
  2. Each time they send invites for the month, they edit the form and add a line to the log sub-form.
  3. I have created a report that can show the person, month, year, target for each metric and totals from the logged data
  4. In order for me to get the option to create a Chart, I have to add Groupings to the Report - these only allow 3 groupings.
  5. When I go to create a Chart, it only allows you to select one of the Grouped fields and then just displays the 'Record number', which is a useless piece of information
  6. I want to be able to add a chart to a Dashboard so the sales team can have this on their home pages
Does anyone know how I can achieve this?

Thanks