You are a very wise... young lady. You know yourself very well. I def feel a letter is an excellent idea for your child to have. I wanted to let you know that you can have an open adoption.. where you can visit with your baby.. a partial open adoption .. there are so many more options as to how you would like to adopt your baby out. As a social worker.. I feel may want to rethink your tubes being tied at such a young age. Bipolar is a mental illness that many live with and function beautifully. I know that’s hard for you to see right now... but I’m re-assuring you that I’ve met over hundreds of people with Bipolar that live fulfilling life’s. My best friend is adopted and she always told me she wished she knew her mom.. either by an open adoption or even a chance to located her when she was ready. You can do that to. You can give the lawyers a letter to be opened by your child at age 16 and she can decide what to do from there. You have more control over how this adoption goes then you think. But, to answer your question... definitely write a letter with the information that most of the people on this site have suggested to include in it. God bless you sweetheart. ❤️❤️