I am starting my very first pumpkin patch this year; so unfortunately, I don't have any real knowledge to pass along. However, I was browsing today and came across this article. Perhaps, you will find some good information in it and/or contact them for additional information. We are growing the sugar pumpkins and this article states to remove the first 2 female flowers on each vine?
I don't know if this forces more female flowers than males or visa-versa, but that one of the helpful tips.
Please, let me know if you get any definite answers to your question. What a shame to have all that growth and no yield. Hopefully, this year will be a bumper crop for you!