How to change myself?

It seems that no matter how much I meditate, practice mindfulness, read dhamma books and attempt to follow the 8fold path etc it only takes one little thing to happen and I just instantly revert to very entrenched maladaptive, negative, and I suppose conditioned thoughts and behaviours.Then I feel lots of shame, hopelessness and guilt etc. how do I work with this and change myself for the better permanently? I've changed a little since I begun about 6 years ago but I'm impatient as life is going by very quickly, I'm getting older and I want to be happy and live a fulfilling life but I keep thinking, saying and doing things that are not conducive towards that. I don't have much hope that I'll ever make any lasting positive change. My brain seems to be wired to fail. How can buddhism help me with this conundrum?