elisa is a hiv test that they perform and western plot is like a double check sort of thing im pretty sure, but i have read alot of the forums and 6 weeks in conclusive, and i dont think that you were even in a risk to be worry about it anyway, the Dr. on this site will tell you that there is very little risk or even none.
at 6 weeks your chances of being infected are less than 5 - 10 % (if you even had a risk). Modern tests are much more sensitive and even in MA 6 weeks is considered conclusive.
. But the fact that yours was negative at 6 weeks is an excellent indicator. Besides, if I remember you correctly you had no risk to begin with, therefore you don't need to take any more tests.