What is the reason for the distress and anxiety the questioner feels on days of reciting the Qur'an from memory, and how can she overcome that, especially since she is thinking of abandoning memorization due to this distress, despite her desire to memorize the Qur'an?

The reason for this feeling may be fear of making mistakes and the desire to recite perfectly. The remedy for this is to strengthen self-confidence, while relying on Allah and having a good opinion of Him, and realizing that Allah will help you memorize His words. A minor mistake does not matter if you have striven and sought Allah's help. It could also be from the whisperings of Satan. The remedy for this is to seek refuge in Allah and not allow Satan to prevail by stopping memorization. Rather, one must strive, supplicate, and seek Allah's help.