"I press toward the mark for the prize of the high calling of God in Christ Jesus." Philippians 3:14, KJV
Do you ever find your mind sometimes wandering off into should've, would've, could've land? It is completely normal to look back in retrospect and question some of the decisions and choices we've made in our lives. "Did I make the right career moves? Did I go to the right school? Should I have done x instead of y?"
While these thoughts are normal, it's not really expedient to dwell too long on such things. Just know that what happened in the past is done and has happened already; Trust and meditate on the fact that God is sanctifying you on an amazing journey. As we grow to be more like Christ, our future gets better every day.