Just adding onto paigek3's fantastic answer above, I also did a personal reflection for my PIP. Yes doing a personal reflection is helpful as this definitely adds a layer of ~authenticity~ in your PIP and gives you ideas on how to branch out your chapters. There's also that need to prove your personal opinion on the matter, thus motivating you to do the best job for your PIP.
Obviously this can't be the only primary research you can use as you do need actual field research beyond yourself. I probably would recommend doing maybe a interview and/or focus group, case study and participant observation/source analysis for your other primary methods. Questionnaires are a bit meh (in my opinion) just because you can't gain much out of it (people don't give out proper answers most of the time).
Since you are using your own reflection as primary research, try and balance things out with secondary research to avoid bias. PIPs need to show that you are a socially and culturally literate student not just swayed by their own opinion. There's a chance of loosing marks if you show bias.
Hope this helps