How can I overcome the frustration of continuously committing sins even after seeking forgiveness, and find a way to stop sinning altogether?
You need to face your sinful desires by your strong will. Sinning is the result of weakness in front of Shaitan and sinful desires. Stopping sinning depends on your will power when you decide to avoid the way of hellfire. Imam Al-Sadiq (AS) said: No one will be weak when his will power is strong.
Wassalam.