I'm in a similar situation and have set goal to myself for when I was hopeful for promotion and when I expect the promotion. I've met that clear to my managers and they acknowledge to be on the same page. I was not a nag or rude but had an honest conversation. Updating resume is also on my to do pile. I don't want to leave and like my current opportunity but not going to keep having increased responsibility for same pay.... I could had just kept my old role and had less stress. There are also non salary benefits to consider but that only goes so far.
I've found that my loyalty is often unrewarded and underappreciated both in professional and personal relationships. I also don't do politics.
There are companies out there that also have initiatives to promote LGBT, women, and other ethnic groups an what not. Not arguing right or wrong, but if you are a woman, with good qualifications, you might be more desirable/valuable as an employee elsewhere and might as well take advantage of it. Might want to Google your industry as it relates to that and rankings if you feel that is part of the problem.
Oh, also, HR department may have guidelines for different career paths with a list of incremental responsibilities, skill set, and time at job guidelines. I have used these to know when to ask for promotions and I have used it to bring it up to my manager during discussions successfully receiving the promotion. This was given to me by another manager but you may be able to obtain it from the HR department or website.
Good luck and congratulations.