Hi, welcome
I think being reflective is a good thing, knowing you should have studied harder is self assessing and not many people do that.
I often wonder about education because like you my grades went down the higher I stayed in school. I only made it to year 10 and saw the writing on the wall and left, joined the RAAF (Air Force) and never looked back. I was able to further my education without stress, an adult income and travel and get a car etc. It all fell into place.
Nowadays there is such a high expectation for teenagers to do high education, to achieve as their only goal, but this isnt realistic, some students find their limit and if that comes about then mental health declines... is it worth it? I dont think so. That's the clarity you need regardless if you accept it or not, accepting it is a personal choice but being pedantic or as you call it "perfectionism" is not being fluid with life and that is the major concern that I identify with here.
Being fluid, flexible could include-
Take a few years off education, find a job and return down the track
Continue what you are doing and study more but be prepared to repeat subjects if needed
Consult school counsellors, its why they are there
When studying harder do it intensely but also take those breaks you need to regroup
Self esteem at your age can come and go. To limit the erosion of it- dont take criticism lightly, defend your honour of trying hard, pat yourself on the back and look for reasons to do that (as I did in my first sentence) and analyse why you didnt study hard eg partying or social events.
Life includes waves, ebb and flow is in everything we experience. To expect ourselves to be perfect is to expect us to not be human. To be realistic in life challenges is to reduce the worry and not expect ultimate scores that are beyond your capacity. We cant all be rocket scientists.
TonyWK
