I am 56 and loved my fantastic daydreaming life. I went so many place and did so many things. I loved it! I have memories from age 6 on.
Well I got Empty Nest Syndrome followed by Mania, leading into a Midlife Crisis. I started reading! I am ok your ok, The road less traveled, Passaged, Self Matters (dr. Phil), now codependency no more.
Slowly the world I LOVED has almost disappeared! I miss it. I miss the me I was!
I'm no psychologist but it sounds like the lessening intensity of your imaginary world is probably somehow connected to your empty nest syndrome. Speaking from personal experience, changing circumstances in real life can definitely affect the intensity of your imaginary world. When I was in my mid-teens, my family and I moved out of my childhood home and suddenly I no longer felt a connection with the daydreams I used to love. It took me a couple of years to re-establish a new set of daydreams. Give yourself some time, if it's been a part of your life for this long, chances are that it won't be gone forever. :)