Can you speak with your guidance counselor about your concerns?
You do not need to have A’s in everything to be a strong student. You do not need to be in advanced everything to be a strong student. And you shouldn’t be starting off the summer preoccupied with your grades.
But your teachers and guidance counselor who know you in real life can help you figure out the right courses for next year- and your teachers especially can give you extra support so you can feel more confident in your study skills.
You’ve got this! But please reach out to the people who see you every day, not a bunch of strangers on the internet!!!