Re ‘some people never thinking about it’: i can’t imagine (though it might be possible) anyone *not* thinking about it. I have been told I was wrong though. So, not sure about potential link between the thought of giving up & depression. I am inclined to think it depends on the presence, or not, of other signs (and individual differences)

Re ‘thinking of plans’: this seems more serious and might indicate a depressive condition. Rather than keeping it to yourself, as you are currently doing, might be worth bringing this up in T.