I am a Ph.D. student and my field is pure maths (analysis). It has been 33 months since I enrolled in Ph.D. I have produced a few papers as well. However, serious doubts have been rising in my mind regarding the quality of work that I have produced, ever since I collaborated with an established researcher, Dr. X of another country. Before this collaboration, I had four papers published in journals indexed in SCOPUS and ESCI (I made sure they are not predatory and have no APC). Additionally, I have one paper accepted for publication in SCI journal and three more papers are under review; one in SCI journal and two in SCOPUS+ESCI journal (again, no APC).
After I finished my collaboratory paper with Dr. X, I checked his complete publication list and noticed that all his work has been published in top-tier SCI journals. I know that he is much senior to me and is well established in our field, yet I feel embarrassed as most of my work is published in non SCI journals.
I talked about this with my Ph.D. advisor and he said that I am just being too hard on myself and he is actually quite happy with my work. However, I still feel disappointed with myself.
So, I would like to ask how to handle my dissatisfaction with my own work and assuming that many senior professors, who are advisors as well, are reading this, what would be your honest assessment of my work.