My mother has tnbc, with nearly full metastasis to the liver. Stage IV. Please, please, right away, do a PET scan of the liver and lungs, including all lymph nodes, and all other major organs if possible, as well as a brain MRI (although, for some reason, it's not easy for cancer to metastasize to the brain).
Do NOT trust liver enzyme levels. My mom's liver enzymes went back to normal 3rd week of June. The doctors did nothing till mid-October. Not a single scan, nothing. Next thing we know, it fully metastasized to the point of being ineligible for even a liver transplant.
Also, do not trust a "bone scan" either. In my mom's case, it came out completely clear, no cancerous anything, and on the other hand, we've got CT and PET scan results that rubbish the bone scan.
Currently, mom's mid-way through her 3rd chemo (Doxil and Carboplatin, combined with Xgeva and Neulasta), we did a CAT scan last Thursday, and the oncologist basically said that this current chemo regimen is useless.

We should have known something was off when mom did not lose any hair the last 7 weeks.