Welcome and you have done a very good first job. You will discover we are our own worst critics! The absolute only way to be better is to make more. Often times our beginner errors result from inaccurate cutting and our 1/4" seams being slightly off. This will improve - I promise. Also, keep in mind that you really don't make mistakes, you are adding 'design elements'. And more often than not you will be the only one who even notices them. Keep quilting and remember to have fun doing it.