I can understand your difficulty. I have come to wonder "who doesn't struggle with it at times?" But I guess not everyone, considering how many vocal people have no understanding of trans* folk or homosexuality as a natural state.
It's really easy for me to declare LGBTQ allyship. I've been feeling a little like a "Me too poseur" with my Daughter coming out as trans.
Now, I'm going to show my big
but (pun intended

)
Every time I'm confronted with M or F on a form, I stop and actually think about it... except when being classified female causes a bit of a controversy, just because I'm contrarian. I answer the question in my head with "I'm female, but not like
other women. I'm different"
I don't want change my pronouns, but usually don't care. I have a "male-sounding" name. I rejected my male name for a time, as a child. I love it when people are surprised I'm female bodied. I like it when people called me a tomboy. I only occasionally wore a dress. I played with masculine toys and preferred the company of boys, but adored stuffed animals. I'm a sci-fi geek and academic nerd. I do most of the repairs around my house. I hate cleaning or any housework, for that matter. I'm not a garage or yard person. I'm "bookish". Since puberty, I seriously prefer a short, easy haircut, but wore it with a long "tail" for 2 decades.
I have little in common with "the average woman", but don't like sports and can't stand masculine posturing.
I don't fit in with stereotypical women but I talk too much for me to fit with typical "guys".
I work in a male dominated tech world. I hate that my uniforms don't fit my curves properly because they're cut for males. I'm not muscular and have a petite build with a zaftig figure. Sometimes I love to get "dolled up". I wore a tux shirt and jeans for my last wedding.
I like being enveloped in my strong, protective lover's arms. I love being a Mom, but don't socialize with "Moms". I loved that I could bear a child and nurse. I'm happy I had a fairly early, easy transition to menopause, but don't appreciate the loss of my youthful appearance.
The whole question, "M or F ?" seems to rile me up to the point that it's best to consider myself genderqueer. But because I have no motivation to change my birth assignment, I wonder if I'm offending trans* folk when I say that I can empathize with some of their concerns.
I don't want to do away with gender. I think it's a convenient way to clarify anatomy, physiology and reproductive potential. Beyond that, I just don't know!
Here, I feel able to relate with people that have their roots in both worlds or have felt uncomfortable being categorized by their genitals or appearance. I hope that you find this a safe place to express and think through your feelings.