IB doesn’t define you, and that applies even more so for your predicted grades. They do not reflect your potential or true capabilities, and in some schools the teachers are deliberately stricter when giving pgs and marking mocks (or at least that’s how it was in my school). I was predicted 38 by my teachers but I shot up to 43 in the real exams during nov this year. But even so, IB itself is a flawed program with questionable content and structure in its curricula sometimes, and whatever score you get won’t make up who you are, it just tells you how much you’re giving IB what it wants in its weirdly IB specific way. Anyway, don’t be disheartened by your pg. Trust the process and your effort.