Is there a way to save my career from absolute disaster?
I think your situation is not unique. If you look around academia.SE (as user2768 suggested, search for "impostor syndrome"), you will find that many PhD students have the same feeling about their work or their career path. See How should I deal with discouragement as a graduate student? for example. I hope this gives you some comfort -- sometimes it helps to know that other people are in similar situations -- and you will find some advice in the answers which works out for you.

The advice of your advisor seems reasonable in the sense that often one looks for the perfect solution from scratch, which is a path that rarely brings the desired results. I found that research is done in an iterative way, where you steadily improve and refine the methods and thereby the results. Of course, academic rigor must not be neglected. The impact factor is in my opinion indeed overrated, but this may depend on your field.

Don't let that stop you from applying and attending job/PostDoc position interviews. If you do nothing, you may end up in a spiral downwards since naturally there will be no progress in your career. And even if you fail at an interview, at least you gain experience what is required to succeed.