Tippy top adcoms will see straight through all that, see the B grades and scores. You made choices. Job prep is not academic prep. Tippy tops want kids who thrive in the classroom, are prepared for the higher bar in classes, once there.
ECs are prt of the equation, but not the sort that barrel down this pre-professional interest.
And just writing a book, maybe self publishing, is not a tip.
You have lots to learn about what the right matches are.