I got better and improved results later of one chapter of my published PhD thesis I defended my thesis in 2015. Later during the preparation of publications from one of my chapter, I got improved and better numerical simulation results than the one in my original thesis. Although almost all the conclusions remain unaltered. I published the modified result in a journal later. Sometimes I feel depressed thinking about that and I didn't make any corrections in my thesis because it was too late, but I have incorporated all the modifications in the journal paper later.

In another chapter 2-3 small mistakes are there during the writing of thesis, but they have zero influence on my results.

Will that create any problem in future? Please advice.
Improving on results is how science works. You should publish the results and be happy you did better!

As for minor mistakes, I would consider adding a short errata section as a supplementary file in your university database (if they allow it), or in your personal website if you have one. In either case this is perfectly normal and standard, don’t feel bad!