Struggle to stay ahead of my workload at work

I am struggling to stay ahead of my workload at work. I can’t seem to keep up with all the tasks. I find myself drowning in end-list to-dos. Sometimes, I get urgent requests throughout the day where it takes me further from getting my original list of things to do at work. I feel frustrated, anxious, and constantly working in a tense and stressful mindset.
I work long hours sometimes, and it’s still not enough to stay ahead. This is not what I expected when I took on this position a year ago. I thought it would get better; it’s getting worst. I want to work at my best, enjoy the job but don’t see how through these circumstances.
Can you please help me process this in a model, and where can I find materials to help me work on these issues in the study vault?