i hear you, really i do. life is cruel at times as to the whys and it's stuff we don't talk about at times. i've got my daughter coming today for overnight, i try and make the most of it -- i hear about you when you say about parties and all that, she goes to more things than i ever did as a kid and i'm happy she's around people -- maybe i assume it's not always the right people but then she's got her own mind and can ask me questions whenever she wants if she ever feels anxious about anything -- that's all we can do as dads, love our children as much as we can.
of course your daughter thinks about you man, it's biological. that never leaves. ever.
the keeping busy is fine as long as you are keeping mentally sane and celebrating life by trying to carve some level of future for her too, even if it's just to put something aside, advice, words, money whatever it maybe -- i think we both have the same run in with mental health!
remember, you keeping sane helps her massively when you are together. have a chilled day man.