Is it possible to move past bad decisions made during PhD and hope for a bright future if I do a good job in postdoc?
First of all, congratulations for your achievements! 

I did not a complete a PhD, not to mention a postdoc, but I had my own bad experiences during my academic and professional career.

From reading your question, it seems you have all conditions to succeed in this new stage of your life/career. Obviously, you had your low moments a few years ago, but you saw with your own eyes they can be overcome. I believe this could give you the extra confidence when facing obstacles later that you can spot them and know how to resolve them by yourself or with help from others.

Regarding obtaining future positions/jobs, I am confident PIs, universities and generally employers do no look that far in the past, but rather focus on the performance of people in recent years. In consequence, I believe you should keep a positive attitude and when the ghosts from the past appear realise they can be again defeated.