Student or Learner
You are a worthy role model. In fact, it has always been a valuable experience. Hence, I could assure you that my academic progress in the last few years/in the past few years has been greatly attributable to your caring attention and careful guidance.
Would it be grammatical if I used has been in such a situation, please?
I would use "My academic progress ... can be attributed to ...". I don't like the use of "greatly" with either "attributable" or "attributed".