How can one get rid of nervousness and shouting at parents, and abandoning some prayers?

The questioner's eagerness to reform herself and her feeling of shortcoming are signs of goodness. She must maintain her prayers at their appointed times, for prayer is the pillar of religion and the first thing a person will be held accountable for on the Day of Judgment. She must be dutiful to her mother, for the mother's right is great, and disobeying her is among the greatest major sins. She must repent for her past acts of raising her voice against her, and address her with politeness, gentleness, and humility, as Allah Almighty says: "So do not say to them [anything that indicates] disapproval and do not reprimand them but speak to them a noble word. And lower to them the wing of humility out of mercy and say, 'My Lord, have mercy upon them as they brought me up [when I was] small.'" She must also strive against herself to avoid anger, for anger is the sum of evil, and good manners are acquired through habituation and practice. And she should frequently remember Allah and supplicate to Him.