I had strep throat 2 weeks ago. I think the amoxicillin didn't work cause I been stressing. Is that possible for it not to work to get rid of strep?

Strep throat. Amoxicillin typically will cure strep throat. Stress will not affect the medicine. If you are still having symptoms, suggest you re-visit with your PCP for an exam. Ask the PCP if a culture was done so antibiotic sensitivities can be checked.
Persistence. If your throat problems persist after treatment there is several possibilities. Patients can be co-infected with a virus that takes time to clear (mono takes 3 wks). You could have become re-infected from re-exposure or your toothbrush, or just didn't get adequate treatment. The symptoms could be something else altogether.