I will be in this situation - I’m 18 on a gap year (not by choice) and will be 23 when I graduate, whereas most of my friends will graduate at 21 and I even have one who will graduate at 20 since she skipped a year!
I think it makes complete sense to be anxious about the situation. I really struggled with the idea of being a year behind my peers but what helped me come around to it was (1) it wasn’t really possible for me to not take a year out and (2) the medics will be in the educational system just as long if not longer than me. Also, stuff happens. Graduating at 23 isn’t massively abnormal by any means, I also have plenty of non-med friends who will graduate at that age or later for many reasons, from poor physical health to going to a Scottish uni. And there will be mature students etc