Have made several mistakes during the course of my PhD. Can't help but feel resentment. Can I get some advice about how to move forward? I am about to defend my thesis. My PhD journey was not a pleasant experience. I worked in an area not within the field of expertise of my advisor. Though she was present to discuss; the conception, implementation and problem solving of the projects were a lonely enterprise. This was disheartening at times, leading to poor productivity during the first two years of my PhD. In addition, my advisor was not prompt in correcting my manuscripts and thesis resulting in poor publication record till date.

As I am about to defend my Phd thesis, I feel resentful about the poor decisions I made by choosing the advisor or by not being more productive or vocal about the need of the manuscripts getting promptly corrected.

I have a postdoc position that I will be beginning from the end of the year. Thanks to lack of connections in my field of research and my poor publication record, I managed to land an okayish postdoc position. I hope to do well and get a better position after. 

I don't want to be resentful and feel self loathing. Can I get some advice about how to make the best out of my position forward?
These "mistakes" are perfectly normal learning experiences for a PhD student.  Feeling resent and self-loathing are not normal.  I suggest you discuss that with a professional counselor.  

It's not your job to tell your supervisor to work faster.