Replying to Giro Shiv sizing question...

My head measures about 54.5 cm (I know, I have a fucking tiny head) which is on the larger side of a size small, according to the Giro size chart. With the goggles/beanie under the helmet with the pads removed, what size would work for me? Also, I may want to size up and keep the pads on the sides/front/back in and only take out the top pad. This is what I did with my POC Receptor, in a size Large. Help me out, NS. huge, important, all-powerful KARMA POINTS shall be rewarded. Thanks.