It is common with any Interest based loan system.
You are commited to pay agreed Interest (say 9%/12month) of the loan balance every month whether you are paying or not paying the principal amount.

But the other loss that you have not calculated is the loss in increased interest by differement of payment.
That may come more than your 2 month Interest installements.

Only Islamic banking can give you peace of mind in such situatuions.