Not sure what to study..

I finished my Bachelor Of Nursing in 2012. I started working in aged care and within 2 years i am the care manager. But i dont see myself in aged care for the long haul.

i am very much interested in mental health.
i was planning to study "graduate diploma of psychological studies" and then doing an honours in psychology to become a psychologist. But i have heard the competition is very fierce in psychology.

Should i just continue doing some course in mental health nursing or take the risk and start working towards being a psychologist.
I am very keen on mental health but am just not sure what to do.

any advice??
What country are you in? Your choice of terminology sounds like Australia.