Probably you have done no damage, BUT, never force a hydraulic device once it hits its end stops - it WILL work hard to push maximum pressure possible, thus heating the oil rapidly, and applying a severe strain on all the components.
If you want to know how strong the power steering is, try taking the drive belt off, and then manoeuvre the car in a small space like you are parking it.
You probably won't manage to steer it at all at low speeds.
Take it easy!
CharlesY