It's really nice to see a few people post things here that are a little similar to my experience. Below, I will summarize my own experience of being species and gender dysphoric.
Around age 11, I developed a severe longing to be a dragon. I had no idea why, and there was no internet back then so I had no support. I think I told my parents but they were just confused by it. It depressed me severely but after about a year I learned to just stop myself from thinking about it because there was nothing I could do to change my body. I didn't stop being sad about it sometimes, but it became a manageable species dysphoria. Even now, ~30 years later, I would still choose to be a dragon if I could, no matter the social consequences.
My ideal dragon form back then was hermaphroditic. Over the years I played males and females but I may have settled on a primary male form primarily because when I finally met others like myself online, one of them claimed they were related to me in a male form in a past life. I only got them to admit that was probably wishful thinking like 20 years later. Grrr.
I remained gender fluid online, but whenever I wondered if I might prefer to be a female human I shut down that thought process because I didn't need more pain and dysphoria. Being both the wrong species and gender would be too tragic.
At first, I tried to convince myself that since my body was wrong anyway, gender didn't matter. So I took a male mate. After a few years I kept longing for female companionship.
Finally, I met and married a dragoness. I was really happy for a year or two, but over time I realized she was essentially the male in the relationship while my behavior was feminine. In fact, she'd wanted to be male from a young age.
The fact I hadn't noticed gender dysphoria at a young age was another reason I never seriously considered gender transition. I now theorize it could have been there, but the species dysphoria was stronger. Then I learned to just stop wishing to change my body, so both conditions were masked. I also now know that gender dysphoria isn't a strong thing with every trans person in the first place. I think "gender euphoria" when feeling you've got the right gender is more universal.
Another reason I didn't consider transitioning was that playing female online was usually mildly uncomfortable. I felt like a fraud and was nervous that people would be mad at me. So I made it clear in my profile I was male IRL. This meant I had all superficial encounters and that I wasn't feeling feminine. On the other paw, when I switched to female with someone I was already close to in male form, it always felt amazing. That should have been a clue.
In my late 30s, I finally went online as a female character without saying anything about my RL gender. People treated me differently and I had a lot more fun. For the first time, I didn't mind being the center of attention or performing in front of a virtual audience.
Then I met a dragon who was looking for someone to roleplay a particular dragoness character he'd invented. I offered to play that character and he agreed, but procrastinated. I thought the problem was him having guessed my RL gender, so I tried making a new character to use to make him think I was a new person. Then I chickened out because I can't stand deceiving people.
Two years later, I went online with the dragoness I created for him. I met him and he agreed to let me play that character. The roleplay quickly took a direction we hadn't intended but it felt to both of us like the characters were in control. This dragoness began to feel real to me, and I began to fall in love with my roleplay partner.
Weeks later, as he pushed for more details of me IRL, I decided we couldn't be in love with me lying to him. I told him who I was, let myself cry while waiting for his response, and he said it didn't matter.
Being a dragoness in love was the happiest experience of my life. It convinced me I had to know what it would be like to be a female human as well. I started wearing girly things, sitting to pee, growing my hair, and working on my voice. Everything I tried made me happy. I found I love to be seen as female IRL, and I am lucky to have a body that allows me to pass at least with those not closely scrutinizing me. I can get very sad when people recognize I'm transitioning.
At this point, I'm 15 months on HRT, have changed my legal name/gender, am about 80% done with facial hair removal, scheduled for FFS, and have been presenting female 100% of the time for 9 months. Sadness from gender dysphoria actually hits me a lot more often these days than species dysphoria, but I suspect that's because I've dealt with being the wrong species for so much longer. I also can't avoid thinking about gender issues as I go about planning and partaking in procedures and worrying about how people perceive me.
Having a dragon body is impossible so it's not as hard to tell my brain to stop dwelling on it. I also don't have to go around worrying if I'm passing as a dragon because of course nobody knows I feel like a beautiful winged creature on the inside. But there certainly was a time in my life when species dysphoria was my primary source of pain, and that pain feels identical to gender dysphoria in my head. I still experience both.
I can feel the dragoness I am now a lot more than the herm or the male I used to think of myself as. I feel her horns, her wings, her long neck, her predatory gaze. At first those things came unbidden. Now, they usually only come when I focus on them. Focusing often makes me sad, so I don't do it much. This all makes me wonder if the dragoness is a past life that I am only starting to remember, and if remembering her makes me all the more keen on changing my human gender. Sadly, there is no way to test such theories.
For the couple people I've seen saying trans-species people sound crazy, I've told two gender therapists my history and nobody has diagnosed me with any mental illness or condition. There is no history of mental illness in my family. I had good parents, no childhood trauma, and I now run my own business and make enough to live comfortably. I don't know if being dragon otherkin is genetic, spiritual, or what, but if it's some sort of delusional disorder, it's remarkably limited and specific. I've never wanted to be anything other than a dragon.