Bill my brother. We have so many of the same issues, haha
Lately Ive been trying black coffee with a tablespoon of ghee. Freakin rocket fuel!!! I not only can concentrate better but have a much better mood and am much stronger at the gym. All signs of increased dopamine.
What's strange is that straight black coffee usually just gives me anxiety and doesnt boost my energy. Black coffee plus fat boosts my energy but my anxiety stays low. Who knows how that works...
What has also helped me a lot is lately I dont allow myself to do ANY internet surfing until after 3:00 PM. Its impossible to give up the internet so I only allow myself direct actions such as return an email or look up an address. The internet is a big dopamine booster but I think it messes with its regualtion. Ive been feeling much more "centered" since adopting this habit. I find it is especially hard in the morning as my mind is trying to wake up and will find any excuse to go online. There are some free habit apps on the iphone and im sure droid which helps make this a reality.
I know that you dont want to try herbs but Im also adding this for anyone who comes across this thread and has similar issues: Another option to try if you are a CA resident is medical marijuana. It boost dopamine and a small german study said it helped ADD. I dont use it often but I find if I eat it I can concentrate well, and can work out hard plus can roll with the punches much better. This is for sativa not indica.
Link to study (will open as a PDF)