It seems you still left out your negative (-) sign in your net loss calculations...

You have used net profit to calculate net loss...

Net Profit = Profit - (investment + Loan interest)

as you are to subtract your investment and the loan interest to have your Net profit.

However the Net loss is different, you have to add all your expenses which are you investment and loan interest, therefore, the formula becomes;

Net Loss = Loss + Capital expense (investment) + loan interest.

Only then can you get the loss of 31,200 USDT, and not the;

Net Profit = Profit - (investment + Loan interest)

You've used in calculating your net loss.