I think you might be overthinking your tarp pitch. One of the advantages of a tarp over a tent is that there is no one hard and fast way to pitch it. The ultimate goal is to erect it so that it will protect you from rain and a bit of wind; if your pitch is taut and leaves enough room for you underneath, then it's good. So I don't think there is a "right way" that you have to get the tarp for it to count as a half pyramid. If I saw your tarp in the woods pitched how you have it, I'd describe it as a half pyramid.
That said, here's how I personally pitch a half pyramid with my poncho tarp. The rear corners get staked to the ground. My trekking pole goes up similar to how you have except with the handle up to keep it clean, typically about 120cm/47". I guy out the front corners next, keeping the lines as close to 45 degrees as I can to keep the tension even. Their length is a bit shorter than what you have. Next I go around and tighten everything and fiddle with the pole to get it taut and to angle it so I have room to get in and out. That does mean I have maybe 44" at the peak, so my interior room is less than that. Finally, I tie off the hood and guy it out, which gives one side a bit more room, which is the side my head goes towards.
And I always vary the pitches based on what's around my campsite and the weather. I actually haven't used a "pure" half pyramid pitch in the wild even though I love it in theory. My most common way to pitch is to vary an A-frame by tying off to trees in order to get some height so my living space. Obviously, practice is most important, of which you seem to be getting plenty, so I think you'll be fine.