Power steering fluid leak help

02 impreza. A couple days ago noticed the fluid was low, topped it off and yesterday the reservoir was empty and I heard the pump "whine" when steering.

Planning to bring it to my mechanic soon, but curious if I can continue to drive while just being vigilant of fluid level and adding as necessary?

Also curious how likely this is the steering rack, cause I know these are $$ to replace. Thanks any response is appreciated.