Just a Mom... fading into the background....

How may Mothers are out there, with grown kids, out of college and either ready to be married or just at that age? One of the hardest things I've found for myself is to leave my grown sons live their own lives. Let me rephrase that. Not really leaving them alone, but to not expect much if any communication back. Is it the times we live in? We all know just oh too well how busy this world is and the demands on people like never before. Ok, I get that. Then we also know that kids need their space and need that time out of the parental units lives to find themselves and grow on their own. That's all good. But what is hard for me it to simply want to gain an adult relationship/friendship, without overdoing, and expecting to be "let in" from time to time... Sometimes I feel I'm only the "mother" now for when they need something they want, like I'm the last option - and that they feel they do not need to respond to me in any form of communication, as thou they can simply not answer or deal with me if they just ignore. How many other Mothers have this problem? I'm sure there are plenty. I am a communicative person and not just want to know how my sons are, I NEED to know, and feel that void or begin to think of all the things I've done wrong to cause them feel the need to avoid. When a person has abandonment issues to begin with... it's just easy to let the mind go to me. When it's not about me, it's about them growing up and building character. I just miss relationship and communication. How many others are going thru this? Just curious. I lift up my eyes to the hills, thats where my help comes from, the Lord, Maker of heaven and earth. Just a season, this too shall pass, they will grow up and want to become more friendlike - adult to adult and not run. I have 3 fabulous sons, I just want to be a bigger part of their lives than they let me. Any suggestions for letting go?????