Informal rent paid to family in the manner you describe cannot be counted as outgoings when applying for a medical card. Qualifying for a medical card in your circumstances will be based on your age (there are different rules for 16-25 yr olds and over 25s), whether jobseeker's allowance is your sole income and how much you actually get.
Sorry for the delay in responding, but medical card qualification is a minefield so I was waiting for information for you.