I get 461 marks and I belong to OBS(B) category do I have a chance of getting a government seat? Or else should I waste one more year?

Well relax there is no need to be feared you should try for admission to govt college based on state quota as you have not mentioned your state i will give generalised view regarding all state quota and AIQ cut off, not possible to get through AIQ  in govt college with these marks and also with these marks getting into colleges with state quota is tough but you should apply to state counselling and colleges of your choice even after that you dont get a college of your choice and you are passionte and clear about doing medical then only you should take a year off for preparation