I appreciate the fact that Disney World is immersing me into a well told story more as an adult than I ever could as a kid.
Your problem isn't age. Its just that you are starting to feel self-conscious. I personally have felt the same. When I was younger and no one else would go on the 3 mountains, I felt really sad having to ride them alone. I was worrying too much about what total strangers thought of me the whole time and it impacted my enjoyment. I still have that issue when I have to travel alone for work. Sitting at the hotel bar alone while watching all these families, friends, and couples together having a good time gets depressing for me.
As nice as it is to be able to do everything on your own schedule, happiness is best when shared. Maybe that feeling is what is really holding you back, not age.