I strongly suspect that I have ADD/ADHD (and I'm looking
for a good psychiatrist in my area to discuss this with
...I'd still like to find a solution that doesn't involve
medication, just as a matter of personal convenience, but
it's been a struggle so far.
Generally, the rest of the answer comes in the form of coping (ie, focus-enabling) strategies that literally apply to anybody in the world whether they have ADD or not.
In my experience, proper sleep is the biggest factor, followed closely by sufficient exercise (which of course helps you sleep as well). Proper environment. Proper task management system. Support and understanding from your partner. The exact formula is different for everybody, I'm sure.
a good psychiatrist
I highly support your idea of seeing a psychiatrist - I just wanted to give a heads up on what a psychiatrist will and won't do. Their worldview is generally limited to the medication itself, which can be incredibly myopic when it comes to ADD success.