I've had this problem and I'd recommend trying to improve your presence, although I'm not sure how this will work with your ADHD.
You can work on presence 24/7. To start, as you go about your day, describe to yourself what you can hear, what you can see and what you can smell. This will bring your environment into your consciousness. When you see a WG, start doing this before you even set off for the meeting. When you're there, keep doing it ... listen to what she says, the smell of her perfume etc. Bring things in the room into conversation.
You can also try to get out of your head the things you can't control. For example you say you worry if your car is safe etc., but once you've taken steps to park and secure it to a level you're happy with, there's nothing more you can do. If you worry about it in your head, your car will not be any safer or at risk so try to stop thinking about it. Maybe next time before you walk away from your parked car, look at it and take a moment for your mind to be happy with the steps you've taken.
I'm no psychologist but I have found this has helped me get out of my head in many aspects whether getting it on with a WG or a meeting at work. It'll take practice but hopefully this will help you get out of the thoughts in your head.
S.