Not sure I'd consider it good advice, but you could just slightly modify your presentation in ways that clearly break norms for guys and make subtle (or not subtle) hints that your mom seems to somehow be oblivious to despite your stepmom seeming to pick up on it despite hearing a lot less direct "hints." Probably easier to just come out, but maybe you could turn it into a game of how direct you can be without one of them seeming to have any clue if they're as oblivious as my mom.