What are my chances of having twins?

Ashley • Will be meeting our first in August 2015!!!
My grandmother had 3 sets of twins and one single birth.
My uncles were identical, my mother is a fraternal twin, my aunt lost her twin brother during birth, and I've got one uncle who was alone in that belly of hers! So that's 1 set of identical, 2 sets of fraternal.
My mom had no twins, of course, but with pregnancies like that, what are my chances of twins?