Since you did not know the correct direction of the Qibla within the mentioned deviation, the previous prayers are correct but the prayer should be, from now on, towards the correct direction of the Qibla, since you have realized that and paid attention to it. The prayer is void if the earlier Qibla is taken, as it is deliberate disobedience.
If you could not find needy Shia believers, you could pass the cost of the food to the offices of the Marja in order to be given as food to the needy believers.