That’s unfortunate that you couldn’t do it earlier and now I understand your earlier comment about not knowing until 3rd year.
All of my surgical subspecialty friends knew surgery as M1s and M2s, which you said you roll your eyes at. I wonder if the difference is at our institution at least those of us that came in gun-ho went straight into the OR in the specialties we were interested in. As a M1 I was spending 3 days a week in the OR. I know others were doing at least one day in Ortho, plastics, transplant, CT, vascular. We also started our research as M1s as well.
When we got to 3rd year we all had already decided the sub-specialty. We also in 3rd year had the opportunity to do 6 week apprenticeships in whatever field, I did all 6 in Nsg and was encouraged by our PD to treat it as a Sub-i. A few people then switched, Nsg to plastics, ortho to uro, etc, but no one out of surgery altogether, and with pubs and time to spend several 4th rotations in the decided field.
I think for most of these fields deciding in third year puts you significantly behind, though not impossible to catch up. Caveat- this is a T5 super academic place so there might just be a more competitive culture with these expectations.