I know exactly how you feel, but your situation is a little worse as I have our 11yr old with us.
My 3 kids from a previous marriage, 34,30 and 26 are back in the UK and I know they are all grown ups but I cant describe the feeling of missing them. And then this eve thought I would skype them (which we do most weekends) and the buggars are all busy! Good to know I am not always in their thoughts though.
Our 11 yr old is fine, made lots of friends and is always busy. I would go home tomorrow, and so would my OH for different reasons, but we are going to give it a couple of yrs (9mths in) for the sake of our daughter... and my sister is visiting Oct then my daughter xmas, so have to stay for them.. It does'nt matter how old your kids are, you will always be their Mom.. The very best of luck with whatever you decide to do, and who knows, when your son visits he may fall in love with the place. xx