Is the quarter system bad?

I’m currently a senior in high school committed to SCU and I’m honestly really nervous for the quarter system. I don’t get the best grades (3.5 unweighted but i have a couple Cs) and am a bit of a slow learner. How screwed am I 😭 and is there anyone who got mid grades in hs but is doing well now? I’m majoring in psych if thats helpful