You've asked me to write down my impressions of the conversation that you, Mum and I had in the garden. The most significant thing – the thing I remember most clearly – is the distinction you draw between depressed thoughts and suicidal thoughts. In that, you said that one can have suicidal thoughts, but not be depressed.
This reminded me (at the risk of seeming too ‘academic’) of Albert Camus’ essay, ‘An Absurd Reasoning’, wherein he explores the thought of suicide without referring to Depression. I tend to agree with you and Camus, but in saying this, I still think a mystery remains (i.e. why may the undepressed think of suicide?).
In your case, my darling girl, I pray these thoughts remain ‘Thoughts’ only for you because (along with Camus) I think we can live passionately in spite of (or because of?) the thoughts of suicide. Thus, I think the distinction you made in the garden is actually a good sign insofar as it is the sign of an active mind that has engaged with the sadness of the world and still choses to live.