How to build my portfolio

im j2 and my portfolio is severely lacking right now. i want to go to med school and i feel like everyone who is applying is going to have super stacked portfolios. i havent done too much currently. i hv VIA hours from 1 organisation, i fundraised money (couple thousand dollars) and ive done a hospital internship, but thats about it. I feel like i havent done much but i dont know what else i can do. especially since i got rejected from a few programmes my school offered. what can i take part in (preferably niche to medicine) to build my portfolio.