My power steering is VERY hard, especially at low speeds and in reverse. Sometimes it acts likes there is no brake assist (seldom, but possibly related). There is a seep (not really a leak) in power steering hose I replaced last year. Seep may be because the hose is pressuring up so strongly. (?) I have replaced a hose a needle valve type thing in the pump and that seemed to help. That fixed the issue but it has returned.
My car has an automatic transmission.
Sounds like the power steering pump valve is failing or the pump veins are worn and causing aeration of the power steering fluid making the system not function at low engine speeds. Try putting the transmission in low and turning with the rpm’s higher. If the steering is still hard, then the steering angle may be off in your alignment. If the higher rpm’s allows the steering to be easier, the I suggest replacing the power steering pump. If you need further assistance with your power steering system, then seek out a professional, such as one from Your Mechanic, to help you.