My, does your story sounds familiar...
I knew that there was something wrong as soon as puberty started. I 'put up with it' throughout my teenage years, blissly naïve that such a thing as trans people existed, then 'tried to be a man' for the next decade, by that stage realising that as comfortable as I was presenting as my 'guy self' (having known nothing else), that the feeling of my body being 'wrong' was never going to go away.
Even after 6 months of therapy and doctors appointments to get a referral for HRT, I *still* didn't know whether I was 'really' trans. Indeed, nowadays, I wonder if there is such a thing -- many people have such different experiences.
But within a week of starting hormones, feeling 'alive' for the first time in almost twenty years, I knew one thing with absolute certainty -- I never wanted to have testosterone running rampant around my body again!
So to answer your question, what should you do? Easy -- find out what the process is to start HRT where you live, and take the first step! You don't need to tell anyone, or starting presenting any differently; what medicines you take is noone else's business. Then, see how things are going -- do you feel better? If so, then carry on! If not, well then you stop! I know it doesn't seem like it when you're stressing out about things, but it really is that simple 🙂