So, I just had my wife search around for someone who could perform tests for OCD, and at the same time, decided to get checked for ADHD at the same time. So, I'm assuming she just did some Google searches for a private clinic. You could ask your doctor for a recommendation. I'd just flat out ask. "I'd like to get tested for ADHD. How do I go about doing that?"
They'll know the next step.
> but a part of me keeps putting that off since I really have no idea how to properly describe the whole thing
Don't worry about that. The tests aren't just you describing your feelings. You aren't a doctor, so don't try and diagnose yourself. I had an irrational fear that I might over compensate in one direction or another that would result in a misdiagnoses. =)
So, when you say you are going to make stuff up, you ignore the fact that doctors know about this. They don't just hand out the medication. You don't just go one time, and that's it. And they don't just listen to what you say. At least in my case, I had to take tests.
The best thing I can say is just be honest and you'll be fine.