DISCLAIMER: USE AT YOUR OWN RISK.
Download Future Transaction History from Binance. As you are only able to download 3 month at a time you need 4 files in the end. Copy them together into one and save it as "CSV" file and use as seperator ";". The first line ONLY needs to be the header. So make sure to delete the headers from all the other files.
Just run the tool and select the csv file. It will calculate the gain and write a file next to it with the gain change for every single day. The last line will be your total gain.
I'm using Qt 6.0