I've only had three instances where my panic attacks were so severe that I started to hear things that weren't there from my time in the military.
I have never had any mental health history or experiences.. but I feel I had gotten close to it with foster care. Remember you will have little humans with a lot of similar and/or different diagnosis.. PTSD, ADHD, RAD, ODD, Depression, Anxiety, in-utero drug/alcohol exposures, trauma, child abuse (physical, mental, sexual) survivors.... How would a child in the midst of their crisis affect your own mental health? For kids, they can cycle in and out multiple times a day, vs weeks or months like an adult. I say this with all due respect to you and your own well being.
Are you open to other avenues where you can have a positive impact without absorbing the negatives that could affect you? My thoughts are volunteering with foster kid sibling camps, or foster mentoring. You would always be the positive to the child, their escape, and still be there to create happy memories for them. I have done this as well as fostering and adoption, and the mentoring was received so much better by the kids, and was really enjoyable for me.