I'm frustrated that I learned how to sew my own pants
Do you regret learning to sew?
No, not at all. I think that's an amazing skill for me to have
Learning skills can be difficult so it is good to put in the hard work. It will help you in the future to know how to do things and make your own life better.  You should be proud and not frustrated
I had to learn through trial and error.
Its hard to get things right on the first try.   Be glad for what you have learned, you have a new skill that can save you money in the future,