3 years post septorhinoplasty - what can be done about uneven alars with a complete break in the cartilage? (photos)

It sounds like you're dealing with a noticeable issue in the alar rim (side of the nostril) post-rhinoplasty, which your surgeon has dismissed as "natural asymmetry." If there's a clear collapse or "break" in the cartilage, this likely needs correction.
The best approach is to get a second opinion from a revision rhinoplasty specialist who can assess whether you need a graft*to reinforce the alar rim and fix the asymmetry. Non-surgical options like fillers may temporarily mask the issue, but surgery is often necessary for a permanent fix.

It’s difficult to even tell which picture is before, and after in the pictures included. All three pictures show alar asymmetry, which was there as baseline.
Consider reposting with a complete set of proper before and after pictures.
If you don’t have a proper before, and after pictures, then ask your surgeon to forward the pictures they took.
To get a proper second opinion consultation schedule those is in person consultations with the other plastic surgeons in your community.
For second opinion consultations bring with you a complete set of proper before and after pictures and a copy of your operative report.
These are all part of your medical record that you can request from your current provider.
Best,
Mats Hagstrom MD