I say sign up for a class and go for it. I have been in a class with three people and one was a male, and no problems here. I think it is great that you enjoy this craft and want to move ahead.
I think these sales people need to be more open minded. (I know I had a shop that won't let me take a class there because I did not buy my machine there, well, they must make more money than they need, that they can afford to turn away a paying customer.)