Hi Steve,
It sounds, first off, that you have a pretty clear vision of what you would like to accomplish in your house design, and have done due diligence on making it workable. I'm glad to see that you have been reading Christopher Alexander, by the way, there is great wisdom there!
From a pro's perspective, if I was approached by someone in this position, my main concerns would be on verifying the engineering and offering and modifications that might improve efficiency or function.
To address the first, have you considered sending your plan out to be engineered by an independent 3rd party? You could send it to Fire Tower Engineered Timber or someone like that and have them verify your calcs. I don't think on a small simple design like what you are talking about it would cost more than a few hundred dollars. Joinery is always a personal choice for each timber framer, but should be able to conform to certain engineering guidelines (ie. these tie beam should bear X amount onto the posts, etc.) without cramping their personal style.
To address the second, you sound like you are pretty comfortable with the house you have designed. It might not hurt to pay someone, be it an architect or builder to consult for an hour or so, look at the plan you have so far and let you know if there are any potential problems that you may have missed.
At the end of that, if you are willing to take responsibility for your design, you can approach timber framers to cut the frame you designed and had engineered. They will just have to apply their joinery conventions in accordance to the engineering. You can also approach architects to make a full set of construction drawings based on your design, which should not be too expensive if what you have is basically sound. Accept and consider all input along the way, but at the end of the day, YOU are the one who will be living in this house, not the architect or builder, so if their advice runs counter to your guiding principles don't be afraid to question it and reject it if necessary.
If you chose this route, you will also have the satisfaction of living in house primarily designed by yourself, as well as saving some money.