It’s perfectly normal to hate your own creative work from time to time. Every creator I have ever known has at some point felt overwhelmed by the flaws and shortcomings of their work. For some, it’s almost part of the creative process. It is perfectly natural to feel discouraged. Many of the greats felt uncertain.
Few of us have to be taught to be critical of our own efforts. But appreciating our own accomplishments is something many of us have to learn.
Read your work. Don’t pick at it; don’t edit it. Read it with purpose and full attention. Read it out loud. Listen to yourself. Figure out what you did well. Figure out what is working. Be specific in your praise. Don’t wait for your friends, your family, your readers, your editors, or your critics to tell you whether your work is any good. You won’t believe them when they do. Decide for yourself. Love it for what it is. Celebrate your successes.
If you do this, you will write better, you will generally enjoy it more, and you will still hate your work from time to time.