A lover?

It sounds like your sense of self. Do you do anything for yourself? You seem very "other" focused, looking for others for fulfillment.

Tbe fantasies of taking care of sick mentors could mean you seek approval, need to be accepted by them, to feel important to them. You have to give something to them, and something as important as their well being ( or in tbe case of patients, sometimes someone's life) to feel valued.

When the fulfillment becomes self-focused, you might not feel so empty.

This is the perfect thing to discuss on therapy. Hopefully you are in the psychodynamic therpary.