Month-to-date calculator for a budgeting app on Google Sheets

Hey everyone,

I am making a small personal budgeting sheet and am stuck now and need your help.

So, I want to write a function that takes today's date (14th of August, for example) and compares it with my spending from the previous month's spending.


Thank you so much in advance, I've been thinking of it for almost 3 hours!

Please check a sample that I created from the sheet below: