Change is a lifelong thing - and just bc you change something about yourself, doesn't mean you will never revisit what that originally was. I too have BPD - from many traumas during childhood n young adulthood (sounds same as you), so I understand how it is to try to "catch yourself before you go too far". Sometimes, i find myself thinking "I cannot do this" - and I have to change it to "I need to find a way to do this". It means I have to analyze and reanalyze everything I say n do both before and after I do it - but it has helped me.