Am I required to feed ten poor people for every oath I took to avoid something forbidden, given that I was unaware of the religious ruling and used to fast instead of feeding, and I don't remember the number of times I took such oaths?

If someone swears not to do something and then does it, they have broken their oath and must offer expiation. If they offer expiation, then swear again concerning the same thing and do it, they must offer another expiation. The questioner, after seeking forgiveness and repentance, must offer expiation for every oath they broke. This expiation is feeding ten poor persons, or clothing them, or freeing a slave. If one cannot find these, then fasting for three days. It is not permissible to move to fasting for those who can find one of the first three options. Their previous fasting will not be lost of its reward.