Writing a letter to colleges about my junior year?

My junior year didn’t go as well as I thought because I transferred to a different school, different environment, different teachers, different grading system, and different group of students (much more competitive). Although this brought my self-esteem down (I mean, really down- I had symptoms of depression- my mother kept insisting that I should see a psychologist but I refused because I didn’t think I was in depression-just feeling bad about myself), I kept pushing myself academically (and socially) by taking the most rigorous courseloads. However, I still got 3 As and 5 Bs in first semester and 4 As and 4 Bs in second semester. So, I am still improving and I am hoping that I will get straight As (except in AP English this year- my weakest subject). Now, I am feeling much more confident about myself. Should I write a letter to adcom? Or, is this not a good reason that adcoms should take into consideration when they look at my transcript?

Also, my freshman and sophomore GPA was 4.0 and I was in top 10 in a horrible school. It offered no honors or APs to freshmen, 1 AP and no honors to sophomores but my teacher lied to my class that it was “cancelled”. However, I still challenged myself by taking advanced classes (no honors), 10th grade math in freshman year, and 11th grade math in sophomore year. Now, I am in a very high competitive school that gives a lot of honors to all students that increase their weighted GPA since their beginning of school. Because of my junior year grades and of the fact that my classmates took honors as freshmen and sophomores while I couldn’t, I am in second decile. I am very concerned that my class rank will hurt my chance a lot. Will colleges understand or still frown on my rank?