Vaffla,

that is a wonderful letter. Your thoughts come through perfectly, and I'm sure your T will be very happy indeed when she reads it.

You did ask specifically for ESL criticism, and that's the only reason I'm going to mention this - "the baby I once was have become the person I am today" should be "the baby I once was became the person I am today", and "raise me up"/"raising me up" should probably just be "raise me"/"raising me" (because "raise up" has to do with physically moving things around). Those minor points don't make your letter hard to understand, they are very minor errors, and other than that, your English is pretty darn native-like as far as I can judge. (I'm sorry if I'm being a showoff, but I do teach English grammar at university to ESL/EFL students, so this is something I know something about, and as an ESL user myself I know that it can be important to get a confirmation that there aren't any language errors.)

And you do have a beautiful turn of phease.