The beginning of a tunic..

I finally got all the pieces of the prairie girl tunic traced and cut out. I had been reading about rotary cutters and mats and that they were easier and faster. So last night I went out and bought a rotary cutter and mat. It seems to be working ok, but it seems that I have to press really hard to cut and sometimes it don't even cut through both, a whole 2, layers of fabric. Is this something that always happens or am I doing something wrong? Any suggestions? Anyway I plan to work on constructing the tunic tomorrow. For this I decided not to make a muslin, hopefully this was not a bad choice.