The recipe demanded great skill, and my mother herself had doubts that we would be successful in making the dish. However, in the end we were able to prepare it all by its self. Which pronoun is used incorrectly?

The incorrect pronoun used in the sentence is 'its self-

It is also written incorrectly since it is spelled itself.

The correct pronoun for that sentence would be ourselves since the speaker and her mother form a plural subject, (we, which is the first person of the plural.) The correct pronoun for we would be ourselves in that particular paragraph