I think it's so great that you don't want to think a certain way just because you were taught it. It's really easy to do that, and so props to you for challenging yourself.
I don't have a simple answer for you in terms of how to unlearn the things we have been taught about gender & sexuality. But I will say that having the intention to be open in that area is a great first step.
I find it helpful to try to be mindful and curious. To notice when a thought/feeling/gut reaction I have is due to something that was ingrained in me growing up (in my family, in my culture, or in the world) but that I don't necessarily think is true or don't agree with. Noticing those thoughts when they come up, and then reminding myself that it is more complicated or less black-and-white than that, is helpful for me as an ongoing practice. And focusing on the curiosity can help me from going into an anxious or obsessive place.
Also I want to say that I don't the goal needs to be to get these things out of your head, and I could see how trying to do so could become quite stressful. I think in order to transform our current conceptions of gender and sexuality, we have to understand well where we are currently at in our culture, and where we are coming from. And so actually have an understanding of the messed up things we are taught up gender and sexuality growing up is key! Does that feel like a helpful re-framing or no?
What are some ideas you have for challenging gender/sexuality norms?