3 yr old has strep throat. looking back, she started symptoms 2 weeks before getting meds. worried that we left it untreated for so long. harmful?

No : Prolonging the thrapy for strept throat is not associated with any untoward effect.

Possibly: You have about 10 days from the first febrile response with strep to initiate treatment and stop the auto-antibody response that might trigger complications.You did not describe the symptoms, but if fever was not present you need not assume the clock started at that point. Complication rate of untreated strep runs about 1/200. Be vigilant and have her re-checked if problems arise.