I really want to study Law at Melbourne so that means doing the JD. But I have so many worries. Can someone please set my mind at ease? I'm worried that if I don't pass the LSAT I won't be able to do the one thing I've always wanted to do. I also always constantly get told that only "the best of the best" get to practice Law because there isn't the most demand for it. I understand that but my fear is that what if I finish all those years of education and I can't get employed, what then?? 
Let me address the latter since I have no idea about studying for the LSAT. Sorry.
What you said in bold can apply to any profession, not just law. Let me tell you about my anecdote in finding an ongoing classroom teaching position; it may set your mind at ease.
I had to overcome some daunting obstacles when I was applying for jobs about 3/4 of the way through my teaching course. I spent my final June/July holidays preparing, fine-tuning and personalising my CV and sent out 10 applications. I read heaps of books and online anecdotes on how to make the best CV possible since I wanted the absolute best chance to land an interview. A month went by and I received many 'sorry, you are not the preferred applicant' emails from Recruitment Online. That was one of the worst months of my life; it was very depressing knowing that all of the years that I spent at university may not amount to anything. I quickly realised that I needed a back-up plan for 2014, just in case I did not land anything.
While applying for a few more classroom teaching positions, I also applied for other courses to specialise in EAL/special education and even an EAL instructor position for the Australian Army, since I knew there was demand in these areas. I also applied for international internships and volunteering opportunities. I was happy doing all of these options, even though what I really wanted was a full-time classroom teaching position. I had an interview scheduled with the Australian Army lined up and ready to go, but early in September, I received phone calls from two different schools asking me to come in for an interview. I ended up landing both jobs and had to pick.

So, what can you take away from this? You just need to try your bloody hardest to make yourself stand out as the best possible candidate for a job and to always ensure you have a couple of back-up plans that you are comfortable falling back on if things do not turn out the way you hoped. The former really is the key, however; you need to have a killer CV and relevant volunteering/work experiences to prove to your employer that you are the real deal. Start volunteering for different places now, if you can. The earlier you start, the better.
The job hunt is always daunting but you need to approach it with care and persistence. Otherwise, you have lost before you have begun.