Am I obligated to pay the amount decreed for my father, even though my income does not cover my basic expenses and those of my family?

You must provide your father with what he requests of money if it does not harm you or those you support, even if it means canceling your subscriptions to associations. However, if providing the money causes harm to you or those you support, then you are only obligated to provide what does not harm you. Seek assistance from Allah and from righteous people to convince your father of your financial situation.