Just finished antibiotics for uti, also have been diagnosed with vaginal atrophy & started premarin, still having burning, could it be uti still lingering or atrophy?

If you developed acute symptoms of burning, urgency, and frequent urination over the course of days, then it is possible that you have a UTI that was not resolved with your last set of antibiotics. But if symptoms have been going on chronically, then this may be another issue. Either way, you need to talk with the doc who last treated you for this.

Burning in urine or vagina?. If your urinary symptoms are gone then so is your UTI. Have a repeat urine test to make sure.