Don't you have a special girlfriend or girlfriends that you call a lot, meet for lunch, go shopping with, and just generally chat about stuff that's going on in your life? Maybe that function is fulfilled by your sister(s)? Have you told your sister(s) about him, including Who He Is?
Pretty much those functions are filled by my sisters but I usually have an extra female friend or two I hang out with semi-regularly and I have the usual assortment of old high school/ college/ had babies together/ work friends I keep in semi-touch with. I pretty much tell my sisters everything and they actually are semi-amazed that their dorky big sister is dating someone with such unlikely coolness. So, I would say that I'm definitely not the kind of woman who can't be friends with other women but it's just not a real high priority for me. I like for my friends to be playmates ( go hiking, go see a show) or mindmates (talk about books, politics etc.)so I'm just as likely to hang out with men as women in any social environment.
"Tell me, what is it you plan to do with your one wild and precious life?" - Mary Oliver