I'm still going through it - in fact seeing the thread on it here on Gransnet when I was googling 'empty nest syndrome' was what made me join this site. That thread is here, I don't know if it will help you at all but I certainly found it helpful.
www.gransnet.com/forums/health/1196664-Empty-Nest-Syndrome
Because not everyone understands what you are going through. I have a friend with four daughters who moved away from two of them once they were settled - and they followed her! Now that she has two at uni and two small GCs as well, her house is occasionally like Bedlam and she could do with a bit of peace and quiet.
My own DS will be back next Monday for five weeks and I can't wait, but although he loves coming home for a rest and a bit of spoiling, we live out in the sticks and I know he would never return to live full-time at home willingly after three years of living in a beautiful city. Facebook is my saviour, I can see the little green dots and know he is still alive and well, but I rarely contact him during term time without good reason. We went to see him this past weekend because he didn't think to pack any gloves or hats, so we went xmas shopping and then met up with him and took him out for a meal.
But when the time to leave him came, I felt like kidnapping him and taking him home, I felt so very sad. I thought I had been doing so well until then. I didn't cry, which is a huge improvement on last year. And DD and GCs will be coming up the following week for a few days, so we will all be together again, although with 'add-ons'. That is when I am happiest, when we are all under one roof, and all feels right with the world. I have started to treasure those times, because I now realise why my grandmother used to be upset when not all of her family could make it for reunions. It's to grab back those precious family togetherness times, if only for a short while.