What's hard is that not all heads are the same shape, so you have to try a helmet on to know if it will be comfortable. I have a similar sized head, and the Bell Kinghead was large enough, but it was the wrong shape for my head and uncomfortable.
I've had good luck with Giro helmets, but: Giro makes two lines of helmets. Those with "acu-loc" are one-size-fits-all, with a maximum size of 61cm/24 inches. These are too small for me. Their other line comes in small/medium/large, and the large goes up to 63cm (24.8 inches), and I can wear one of those. The model I chose is the Eclipse.