What part of the country are you in? If you are in the bible belt, you might need to look outside the bible belt to find someone. Also, try your local freethinking/atheist group. I met my husband through an online dating site. I listed myself as an atheist and made it clear that I was an atheist on my profile. That way I didn’t have to waste my time on first dates with bible thumpers. We will be celebrating our 11th anniversary next week.
It seems to me that nerdy-types and males are more likely to be atheists – or at least say that they are atheists – not agnostic or “spiritual but not religious” or “don’t like organized religion”. There are female atheists out there. Don’t give up on the agnostics, either. They might be worried that if they say “atheists” they’ll chase all their dates away. There are quite a few closet atheists out there, masquerading as something else.
Good luck to you 🙂