cassandra fortin removed from hartford , connecticut , home in january .
she was forced to undergo chemotherapy to treat hodgkin 's lymphoma .
her mother jackie had supported desire to explore natural alternatives .
but state ruled teen was not legally mature enough to make the decision .
on monday , cassandra was released from the children 's medical center .
she said ` i 'm so happy ' , adding that the feeling of fresh air ` is wonderful '
teen was reunited with mother in april for first time since the new year .
cancer is in remission , but she says she is happy she ` fought for my rights '