I am assuming you are 4 year trained then - that is really the most crucial point - not 3 year + NQT. Where will your boyfriend be? Will he have a job somewhere? As I said, there are vacancies for teachers but in places like Norseman or Wee Waa (just names randomly picked from my brain but giving you a clue about the sort of places that you may find yourself). If you are prepared to go to some really out of the way place or to a school with a really hard core clientele then you are more likely to get an offer.
I dont think having a boyfriend is going to affect your chances of getting a visa (not negatively anyway unless they dont want him back

) although they do expect working holiday visa holders to leave at the end of their time here. I dont think you would get a teaching job on a WHV either. The money thing could be an issue if you just want to hang around and wait for some teaching to come up but if you are prepared to do anything in the beginning there are loads of jobs in hospitality and retail for the short term, mainly in the bigger cities anyway.