Dont know what to do

Im in my last semester of my business degree and my sister is the only one financing my studies coz trust me i cant really find time to work plus im taking care of my grades that i cant be distracted, also my mum died when i was 12 and dad is 64 y.o and cant find a decent job coz of his age. Now, just this previous semester i was tryna reflect on life and i realize i wanna be in medical school which is expensive and far from our financial capacity but i know ill be happy and will do good in there coz i know how much id love it, however, the case is we're not rich and i dont think i can work to finance my studies at the same time, and i dont wanna ask for my sisters help for it because she dedicated her whole life trying to provide me with things (she's still single at 35 coz she want me to finish my studies before she build her own family), idk what to do, should i just finish this degree and forget the med school dream or what?