my fiance is a u.s citizen but i am an Australian citizen, how could we get myself to the u.s without doing the fiance visa?

If you have or can obtain a visa to travel to the US, you could marry here in the US and then file to adjust status from here.  You cannot get married right away, however, because the presumption will be that you entered the US just to get married rather than on the terms of the visa you were issued.  The fiance visa is the best option.