I miss my son in advance. It sounds daft - he has just gone up to bed, he is at home while he recovers from a torn tendon from going skiing but in three weeks he will have to return to university. He only left home at the end of October, but after only a couple of months he told me that he now thinks of his new city as 'Home'. I felt so sad, but hid it. Of course, life is exciting and full of possibilities. I want him to do well. But I have been in mourning for his childhood for over a year now, anticipating the end of his school years and his needing me so much. I am no longer the centre of his universe and never will be again. I miss my daughter too, but he is the youngest, the last to go and we are/were on the same wavelength.
That poem is very helpful, as was the previous one about the boy wandering off back to his prep school after a match. We love them therefore we have to let them go. We don't want them ending up like Timothy, played by Ronnie Corbett, after all!
Or do we? 
As for communication - when he was off skiing, not one text or call or fb post. Nothing until his final day when DBH received a text saying 'I'm only a little bit broken'. It doesn't bode well.