Argint Sekhem,
Welcome. I can relate to your post in many ways.

I have a tendency to brush off or minimize accomplishments or progress I make. So much so that often if I mention them to my therapist she makes us stop and review the good that occurred. Or my therapist will give me "tools" to use and I use them for awhile, but fail to acknowledge the good they are doing. Then I give up on using them and I am right back where I started. I also have the tendency to give more weight to my failures than my successes. I tend toward perfectionism - especially in areas where I know people may judge me.

Sorry I don't have any words of wisdom other than you are not alone in what you are feeling.