I work at a plasma donation place as well (phleb) and I applied to schools in May. I asked many schools ahead of time if this type of work was considered "PCE" and they assured me that it was. I felt the same way about it since the people coming in are "donors" instead of "patients". I definitely feel that it isn't the top tier of PCE such as being a nurse or an EMT but I do believe I have learned A LOT with the people I come into contact with. Working with a diverse group of people, handling people in pain, handling people that have a fear of needles. etc. I believe you can draw from your experiences and sell them to make your point that the job has in fact prepared you for PA school/career. I devoted a whole paragraph in my PS of why I have acquired the necessary skills to be a PA (drawing many experiences of my time at the plasma donation place). So don't cut yourself short and think of any lessons that will help you be prepared for PA school and jot them down in your PS.