i've wandered over from dude-land to come share the things that i used to do with my hair when i was presenting as female - hope i'm not butting in!
anyway. i've gone through my fair share of damaging hair products, and i can tell you that there was nothing that ever worked better for me than a good trim and an even better conditioner. i used to use the herbal essences "hello hydration" conditioner, and i swear that stuff worked miracles. not only that, but you can get it at the drugstore.
a few ladies have said that you should wash your hair less - i've never lived by that rule. i
still wash my hair every time i shower, which is usually every day. i've never found reducing the amount of times i wash my hair to be helpful, in fact it just makes my hair more greasy. on that note, when i had long hair, i would avoid the "deeper-cleaning" sort of shampoos, such as head & shoulders. when my hair was long i found that using head & shoulders would dry out my hair more than washing it every day did. hence why i'm going to stress the importance of using a conditioner! i went through a wide array of conditioners, and my hair always looked better when i used them. my favorites though were frizz-tamers by companies like pantene, and ones that included hydration formulas by herbal essences. suave also has some pretty good conditioners, the strawberry one in particular was a favorite of mine

about the trim - i can definitely see why you're hesitant about it, but i learned the hard way that sometimes you have to sacrifice length for style. before coming out, and when i still presented as female, i had my hair the same length as yours, and let me tell you - the possibilities for hair that length are endless. not to mention the fact that your hair will grow faster once it's healthier

i used to straighten my hair, but i didn't use a flat iron... i used a curling iron. haha i know it sounds weird, but the results, at least for me, were much more desirable than those a flat iron could have given me. when i used the curling iron to straighten my hair, my hair ended up being more bouncy and easier to style, whereas with a flat iron it just turned rod straight and lifeless. i used to do this every day, so when i started to see my hair slowly getting frizzier... and frizzier... and frizzier, i decided to try out a few products. i found the alberto miracle mist heat defence worked like a dream, and not only did it protect and defrizz my hair, but made it glossy, too.
that's all the stuff i can think of right now, but if you want to know anything else, just send a pm my way!
p.s. you're stunning, and you look absolutely gorgeous with curly hair!