Btw, I really dislike "trans feminine" as its so othering, its one of these language things that in a nasty way is pushing trans women away from being ACTUAL women.... Just a nitpick I guess. The point being, transgender existence is obviously a spectrum, but its simple, people just make up make believe titles to everything these days. There's three things, men, women and non binary and latter covers everything that's something other than, its not more complicated than that.
Your experience and needs seem to land somewhere in the non binary spectrum and that's totally cool, maybe (partial?) medical transition is the right way to go then? HRT will give you the whole package, then its genetics and tweaking your hormone balance and a bit of luck which determines how much changes you get. For maintaining erectins, I suggest you practice a LOT! Keep it working by using it and then supplement with viagra when needed, its absolutely doable, albeit not the easiest to pull off. Lot of non op trans women who like their male parts keep it functioning like that despite being on HRT.
You maybe want to look into a typical HRT program which would be for example, Estradiol Valerate injections, progesterone on 100-200mg per day and some effective testosterone blocker on smallest needed dosage.
Injection is the best easily available method there is and you can even get it very cheap from the grey market if you will. Depending on which estrer it is, that determines the injection cycle, for EV (valerate) its typically from twice a week to once every five days. For EEn (enanthate) its once a week to once every ten days or so. EV and EEn are the most typical types, but there are several even slower acting ones which have longer injection cycle. I have settled for EV every 3.5 days, so twice a week, that way I avoid the severe highs and lows as for me stable levels are the best for both body changes and mental health and it means less mood swings. Knowing which of these is the most practical is about just trying them, I tested EEn but it felt like my body doesn't metabolise it well for some reason, whereas EV works extremely well, but of course its a bit of a hassle to inject twice a week. Usually you will get to do it on your own, that's the easiest way. There's a bit of learning curve but its very simple once you get a hang of it.
The injection is typically done subcutaneously, meaning injected to fat deposit. Typical best spot is upper part of buttocks, in my case at my hip or upper part of thigh as I'm not flexible enough to inject back there on my own. Also lower tummy is good, below waist, into a fat deposit. Another method is intramuscular and that typically means injecting with longer needle to your thigh muscle. This gives higher highs and lower lows as it metabolises faster than subcutaneous injection. Typical needle for SC injection is for example a 30 gauge 12,7mm insulin needle. I use the old fashion ones with permanent needle, that has almost no deadspace so no medicine is wasted. The length of the needle means its deep subcutaneous which I think is the nicest method. For IM, typical needle is a bit thicker and 25,4mm or one inch long to reach the muscle. Both are quite painless when you get used to it, but SC is even nicer as very thin needle works just fine.
Injecting is simple, cleanliness is top priority. Needle should never touch anything except the vial cap and the injection spot. I always wipe the vial cap and injection spot with disinfectant and never toucht the needle with anything, they're single packed and sterile so they're clean unless tainted somehow. For getting air bubbles out of the syringe, google it, there are good video instructions for that. Shaking the syringe in correct way will gather all air into one bubble, then you can let it float to the top and gently squeeze it out until a tiny drop of medicine comes out, this way you will never accidently inject air into your body. We're not hitting veins, but this is just a precaution.
I hope this helps.