I relate to your schedule problem. My dh’s schedule has been crazy over the years, and it really makes it hard to commit to things. I do have children, but I can tell you I feel like a visitor in my parish. You are comparing child-less people in your 40’s to childless people in their 20’s. True, there are alot of differences. But let me tell you, I am a homeschooling mother of young children. And I look around the church and feel alone. Either everyone’s kids are teenagers wearing miniskirts, or the families with a child my age only have 1 child my age - no one has them close together, or has anything in common with my values and philosophies (based on initial conversations I have, which NEVER lead to any further socializing). My point is that you may be surprised that alot of the people you look at as the “involved, happy with their community” people - these people MAY not be satisfied either. Just because a mom looks busy and social (because she has to take her kids places) doesn’t mean she isn’t as starved for community as you are. For me, it is reassuring to know that I am not the only one feeling that way.
One suggestion I have is for you to attend daily mass as much as you can. I think feeling like you’re not a visitor can at least be partially acheived by becoming more familiar with the other active members in your parish. And given that your schedule might make it hard for you to find one group and attend regularly, daily mass is where you’ll be able to see the most people the most often. (This is of course aside from the spiritual benefit you’ll receive from God at mass).