Being related to mint, oregano probably could be a bit agressive.
If it is doing well, it sounds like you have lots of oregano treats on the menu. lol
I keep mine in a pot. It seems to do better for me waterwise.
After reading this thread, I was working outside this past weekend and it made me notice the perennial herbs still growing.
Oregano is one. Bay laurel is another I love.
Both an upright and a trailing rosemary are in bloom right now.
A nice green patch of soapwort.
Many wouldn't consider it an herb but garlic is one also.
I also started some annual herbs this weekend.
And I'm overwintering a few in the greenhouse.
Lemon grass, allspice and a new pot of catnip for the girlies.
If they'd only leave it alone!