Beforehand please check the following sheet.
https://docs.google.com/spreadsheets/d/1gIN3Xvg59B8awxjhjjH6GxMMCY_wrvh8v6uQMVlzj68/edit?usp=sharing

I'm trying to use SUMIF or any specific formula that shows the total amount of income of each month over on the side (March, April, May...)

As noticed the date (month) is not always the same on each column, it may vary.

Is there any way to do this?