Dear

(1) Stop blaming yourself, it seems that you are accepting yourself as the only reason of all these things, you are not. Blaming self results in low self esteem Please Stop blaming yourself by naming Bad Luck , Bad Times Struggled life etc . A best shot of yours will always bring Best result. I would say take it like this the present phase of your life is preparing you for very challenging and stressful career of a doctor (Have you see how they work in any of Emergency or Trauma centre)

(2) Don’t get in to the reasons for which you are feeling  your study is being affected , Like the issues of property and internal parental issues , think as if you are the only one and you have to take it on by all yourself   . You have to bring out that courage which is very much in you your self.  

(3) There is saying in English if you are watching your aim rest of the hurdles in the way gets invisible so small issues like your kid brother should not bother you. If you really want to be a doctor than this single reason is enough to crack the entrance. If you don’t want to be you will find as many as you want.  

(4) About the coaching classes talk to your parents, have courage to do that and show them your confidence and you true aspiration of becoming a doctor. They will surly come up with an answer if they don’t again it’s you who is going to find out a way out.

Best of Luck for your future.