Do we have a case? and how do we do something about it? medical negligence?

ok my girlfriend, a few weeks ago had a rod rod implant contraceptive put in her arm, once the procedure was complete the doctor told her it would be safe to have unprotected sex after 3weeks, and she kept drilling the the waiting period into her of 3WEEKS! in this same appointment she also was written a script for an antidepressant medication she has been on for a few months now. so following the doctors recommendations we waited 3 weeks, but the doctor didn't tell us the antidepressants she is on can affect the rod for up to a month! my girfriend is late and and has 1 positive supermarkt pregnency test and is going for another test at(with a differet doctor) today, shes been pregnant once before and is feeling the same way she did then(she misscarriaged at 5 months) so she is most likely pregnant. we are only 17 and cant handle a child right now we need to finish school and we cant rely on our parents nor can we tell them, they would dissown us.... can someone plz help? btw we our in australia nsw if thats makes a different on laws and ethics or something