I'm pretty sure that chasing achievement in order to feel better about yourself is yet another defense mechanism. In general, NTs are more prone to do it, SJs as well, than NFs. NFs tend to become codependent more as defense mechanism; investing "too much" in relationships.
Anyway, that's okay. But IMO only temporarly. It can't make you happy long term, regardless what you achieve. Problem is when you're at the point where you seem to be now, when you believe that that's real; that self-worth is realy related to achievement. I've been on/off at that point, and it was usually when I had some underlying issues..in my case unhappiness about relationships etc. this is why i know it's false belief... unlike some friends i know who are like that whole life, ex. 2 INTPs, and aren't aware that it's defense mechanism.
what i'm trying to say, need for prove your self-worth over achievement doesnt come out of nowhere, it's related deep feelings, which you should work on... ex... try to look at your younger self and see why you wouldnt like him unconditionaly..