When you find yourself ruminating on some past imperfection, recognize that whatever you did, you did your best. And even if your best was not enough for others, it is enough for you. What else could’ve you done, be better than you were at that moment in time?!
Wake up to the impossibility of that! After all, to be better than you are (at a given moment of time) is to be different from how you are (at a given moment of time).
But you were what you were. How could’ve you been better than you were when you were what you were?! Of course, you couldn’t have!
To think that you could’ve been the you that you were and a better (i.e. different) you at the same time … is just nonsense.
So rest your mind and toss out those shoulda, coulda, wouldas. End of story.