If increasing your femininity hasn't worked, if only partially, becoming more feminine or an out transwoman, probably isn't going to help in all honesty. If small changes don't produce small benefits for your dysphoria, you can't realistically expect big changes to create big benefits. The fear you feel is instinct, and a warning. A warning to try and make sure you're not looking at the complete transition as a form of escape from your problems. Alot of people have hope that once X happens, their lives will completely change. But it won't. You'll still be the same person with the same life problems. Which maybe multifaceted and complex.
As far as motivation goes, the right diet and exercise can be very beneficial. Staying busy is also critical. But its difficult to get started when depressed.
Tell your father you may have "gender identity issues." The word "transgender" will lead him to think full blown transexual. Which isn't what you want him to think from the start. Stay vague, and let it sink in gradually. When he gets to one stage of acceptance, you go to the next.
And of course there's the therapy option. As for if you can stop being trans as an adult? Yes by all measures. There are detransitioners, so they stopped.
You're not going to unlearn your male socialization. That's in your subconscious by now. If changing yourself on such a fundamental level makes your brain hurt and if it seems seriously daunting then don't learn those rules. Theyre gender stereotypes anyway. Remember the end goal here is to make you feel better. If it's not doing that than it's doing nothing for you.
Caveat: I haven't transitioned nor have I seen a gender therapist, so I'm not an expert.