1998 Pontiac Grand Prix a grinding noise when i turn the wh

i hear and feel a grinding noise when i turn the wheel. i added power steering fluid the resivour because it was low and it was making a loud winding noise when i'd turn the wheel. the winding noise is a little more quiet now but now im feeling the grinding in the wheel expecially when i park the car. i dont feel it when im driving normally like around town, just at slow speeds. i dont know if its the power steering pump or the rack n pinion, im clueless. it also looks like my rack n pinion has a slow leak in it. but if you could please help me out, i would appreciate it.