'I wish I knew' passes the buck, responsibility-wise. As if it's some unattainable thing, outside of yourself, a thing you could know, but for some reason, cannot know.
If you can't think of anything that singles you out as the baddest bad in the whole damn town, then there isn't anything. You would know what it was, if it was there. You can't think of anything that makes you deserve less than others. So have faith in that opinion, rather than thinking that there's something about you that's going on without you knowing. Having faith in that opinion could be called respecting that opinion. Respecting your own opinion. Your opinion isn't worth less than anybody else's, right? Because you can't think of anything specific that would make you have stupid opinions.
The way you view yourself is based on a fantasy of you being faulty. I've been where you are. It's a mind shift at the very foundation of your world view, and when it moves, it can't go back.
You have to realise, in the nicest possible way, that there is nothing wrong with you. You are completely normal. You are just as boring and standard as everyone else. Some people will find you awesome, some will find you irritating, some will think you're wise. some will think you dim, etc etc. For me, recognising that I wasn't special or different for having had a tough childhood was enormously reassuring, but it also took away my safety net. Because that's when you have to start looking after yourself, rather than blaming everything that's wrong on whatever invisible fault it is that you think you have.
Your opinion 'I can't actually see anything that's wrong with me' needs respect. If that's what you think, then there's nothing wrong with you. Respecting that opinion yourself is the shift in mindset that will move you out of this rut. It's the kingpin of respecting everything else about you. The kingpin of self respect.