I completed my PhD in mechanical engineering last year. It took me 5.5 years to complete it. I already held a master's degree previously albeit in a different research area. The main reason was my inability to understand the topic, develop ideas and carry out focused work during the first 2 years of PhD.
I got disinterested in my topic/research area early on in my PhD. This was mainly because I had to self learn many advanced topics which were not taught in my university. That made me less sure about my knowledge.
However, post 3rd year, I worked hard, got interested in the topic and published 2 papers in decent journals.
In addition, I did very few TAs during my PhD because I was unfocused during my first few years and couldn't invest time in any other activities.
Now, I am pursuing a postdoc with my PhD supervisor on a different approach to my PhD project which is interesting and will help me secure better positions later. I plan to use this time to publish 4-5 papers.
Will the ghost of my past bad decisions made during PhD haunt me and affect my future even if I do a focused and productive job in my postdoc?