The best engineers are obsessive, but that doesn't mean they suffer from OCD, which as you said is an anxiety disorder. It is one thing to obsess about details of a circuit, to make sure every parameter variation has been verified and simulated or tested and that no failure mechanism has been overlooked -- that is called being thorough. It is quite another thing to repeat the same behaviors over and over, especially when the purpose of repeating them is simply to avoid or to relieve unfounded anxiety.
Another acronym that I think we overuse is ADD. In my observation, the best engineers are able to hyper-focus when they need to -- dive into a task and get completely immersed in it, shutting out all other distractions until the task is completed. Hyper focus (too much attention) is often considered to be a symptom of ADD, even though we tend to think of ADD as an inability to focus. But it's only a "disorder" when it becomes a problem, or when it exceeds some threshold that we collectively think of as normal behavior.
It's ironic that those with an inability to focus for long periods of time -- those with more typical ADD "distraction" tendencies, are often seen as being successful multi-taskers -- people who seem to be able to make regular incremental progress on multiple tasks, even if some of those tasks fall behind schedule and some never get completed at all.
The ideal engineer has no "disorder" at all, but has a tendency to obsess over details to the point of being thorough, and has an ability to tune out distractions and focus attention for a prolonged period of time to accomplish a difficult task.