I know you have looked at Xero and QuickBooks but a lot of users use those for their accounting and expenses. Even though Jobber does handle invoicing, Xero or QB can also handle expenses, tax, payroll and overall reporting on cash flow.
I think we have some discount codes for QuickBooks Online and might have some for Xero soon. That might help get you started so you can try them out and see how they work together.
A good Excel sheet is not a bad idea either, I'm sure someone here would have a good one they might be willing to share.