I really felt this in my soul. I am an INFJ personality type and I started working in healthcare only a little after I turned 18. I experienced something really similar to you; I am great at prioritizing patient feelings and safety above all else, but when that is unsuccessful due to kinks in the healthcare system and such, I feel defeated and drained. The nice thing about our personality type though, I noticed, is that regardless of say working a ton of overtime and being tired or even just feeling defeated and wanting to give up and not care like some of my coworkers, I am always able to push through and give good care regardless of my feelings out of my empathy for the patient. I would say this personality type makes for a good nurse, you just have to learn how to expel the negative emotions you can absorb in the workplace and maintain balance mentally, and physically.