i'm trying to make some roses but they need to be big, the thing is i don't have any rose cutters and i'm afraid is to late to order them i do have the little ones fron wilton and the ball tool and foam pad i need to make the ones in this picture an it will be my first time doing these kind of roses any help?

You can use either circle or heart shaped cutters.
So long as you have a smaller and a larger cutter you are doing good.

I often determine the size of my petal by the thickness of my paste..

So say I only had one cutter. So I'd cut out one set of inner petals the correct thickness. Then roll the gum paste out thicker, cut out the petal then roll it to the correct thickness in so doing make it larger when it thins out.

Works for me.