All perfect praise be to Allah The Lord of the Worlds and may His peace and blessings be upon our Prophet Mohammad and upon all his family and companions.
Facing the Qiblah-Kaba-is one of the conditions of prayer being valid since Almighty Allah says, "Turn then Thy face in the direction of the sacred Mosque: Wherever ye are, turn your faces in that direction."{Al-Baqarah, 144}.
Whoever prayed facing the incorrect Qiblah after having strived to make sure that he is praying in the right direction or after having asked a trustworthy person in that place, but realized, during prayer, that he was mistaken, then he must pray again. However, if he realized his mistake after the time of that prayer had passed, then he must make up for it according to the stronger of the two opinions of the Shafie school of thought.
Al-Imam An-Nawawi(May Allah have mercy on him) said, "According to the stronger of the two opinions of our school, whoever strived to make sure that was facing the correct Qibla and realized, after the time of the prayer had passed, that he wasn`t, must make up for it. However, if he realized his mistake during prayer, then he must repeat it."
In conclusion, the above questioner must repeat the prayers that she had offered facing the incorrect Qiblah; particularly since those whom she asked were unaware of the correct direction; rather, they thought they were. It is worth pointing that Allah will reward you for the prayers that you had offered facing the incorrect Qibla because you were keen on pleasing Him. However, you must repeat the prayers that you have performed facing the incorrect Qiblah to be on the safe side before Allah.And Allah knows best.