Having been both a son and an (step) parent, I know all too well the emotional kick to the gut that comes when a parent shows in an instant that they really don't understand you. We have all been there. It is easy to let an emotional moment become a stand-in for the relationship as a whole, and pop into your head every time you think of your dad.
Seems to me that you are experiencing one of the more unpleasant features of what is in essence, a normal rite of passage. Your father is a flawed human being, just like you and me, and he will not see eye to eye with you on every issue, and remember too, that in raising you, he is probably over correcting in reaction to things that he felt his dad did to him.
You might be too young to see your dad as a son himself, and then an uncertain young man, taking on responsibilities he didn't know he was up to at the time, but he is all those things at the same time that he is that large shadow looming over your life that he will always be, your father.
Maybe you can take a second to list in your mind the other areas in your life where you and your dad see eye to eye, and in fact other areas where you enjoy each other's company, and remember that at the same time you are feeling the sting of his disapproval, that all of these other aspects of your relationship are existing in real time, as well as in the past, and likely into the future, even as the part of the relationship that is bothering you is pressing its way to the fore of your heart and mind.
Remember too that this is a long game, and things change, and one day the things you do and believe now, and continue to follow, will one day be revealed to your dad not only as valid, but as better than the things he wanted for you. This is actually possible, even though at the moment it seems unlikely.
And even if you never receive verbal or overt credit for the wisdom of your views or actions, remember too that you will grow in strength and conviction, and there may come a time when you have such strength in your own convictions that you have no need of parental approval, and you can just love your parents as they are, flawed as they may be. This can take decades though.
It was not until I was the primary caretaker of my father in his final years that I was able to see him simply as a man, a former boy, former schoolmate, former newlywed.
Just a guy, like me.
He was starting to show serious signs of dementia, and so I had to take over many of his responsibilities. Now one of my bones of contention with my father you may find familiar. He never gave me any encouragement ever. His assessment of any situation in my life that I shared with him always seemed to take the same familiar theme:
The best possible course of action was always the opposite of the one I had decided on for myself.
This would explain why he could never train dogs either. He was great at scolding, never praised though. He even got kicked out of a dog obedience class because he just couldn't get the hang of approaching something smaller or weaker than himself with positive feelings .
So anyway, here I was dealing with his taxes or whatever because his mind was too scrambled to deal with them, and he STILL felt like he needed to go over what I had done before he let me mail it off. I finally told him that he would have to trust me, since letting him review my work would mean he would shuffle it all up scribble on it and I would nearly have to start from scratch.
He didn't like relinquishing this control, just barely allowed it in fact.
And I came to the realization that all those years of correcting and undermining of his had nothing to do with me, since even when he got it all wrong and made a mess and scribbled everything up, emotionally, he still felt the need to do it.
I don't know if I am being clear here.
It was something inside of him, and about him that made him do it, and because he was that looming shadow called DAD, I never figured that out. I always thought it was something about me.
He was just a guy. Imperfect, flawed, with his own compulsions and complexes and blind spots. It was the fact that he was my father that had blinded me to that obvious fact. And it only took me until I was in my late forties to figure it out!
So, yeah, it hurts, when you work hard and the people closest to you don't understand or appreciate it, and even with that, there are probably other aspects of your relationship that are pretty good, and maybe later you will be vindicated, or at least appreciated.
(Hey Dad? Hear me up there in heaven? Exactly which one of your children was willing to be your primary caretaker and protect you from Mom? What's that? That's right, it was me. The one you always said had his head in the clouds. Yeah, he was the one changing your diapers. Big ups to me. Heh).
You sound like you got a good plan. Don't let it be ruined by a situation so common it has its own meme:
Shine it on and carry on.