Daily Allowance Calculation From Previous Daily Spending Against A Daily Budget

Hey there I have been making a spreadsheet to use for monthly budgeting while at University.
I have tried to make a formula that will tell me my daily allowance worked out from my daily budget plus interest on savings.

However I wish this budget to compensate for previous daily spending.

For example if i spend under my budget one day i wish it to increase or vice versa.

Please could anyone help out with this problem, I have attached a version of the spreadsheet (The yellow boxes in the left are where I am going to put the finished formulas.

Many thanks!