"Letters from home are messages from a shore we are forsaking."
- Milan Kundera, Life is Elsewhere
I finished the car with five days to drive from northern New Mexico to Seattle. I pulled out of the driveway in a vehicle I'd made from the framerails up. It was about 5 o'clock; my mother waved. I was about to turn twenty. I spent another five days under their roof for the rest of my life, and have spent approximately two weeks within a hundred miles of their homes in the past 25 years. I mention this so you have some perspective on my ability to get along with my family; my advice is external to the situation and not one of experience.
That external observation, however, leads me to suggest that the life of a child that has never left home and the life of a child that has come home are two entirely different things, a situation that parents are less likely to be aware of because their experience has changed the least. Or, contrariliy, a situation that parents are more likely to be aware of because you've been gone and now you're back and they miss what once was and they want it so badly.
The fault-free way to express your experience is to say that your inner life has grown substantially since you last lived at home and while you want to make time for your outer life, which includes your family, you also need to make time for your inner life which does not. This is particularly hard when the physical space that used to contain everyone no longer does but it doesn't negate the fact that your persona has incorporated more independence than the last time you lived with them.
And maybe that's the best way to put it - let them know that you need to be able to feel independent or else you won't feel like you've actually grown any and that feeling independent means not having to hide from contact. Promise them that you'll seek them out whenever you can comfortably give them your attention and time and ask them politely to let you seek out your own headspace.
Teenagers for generations have resorted to headphones, by the way. They don't need to be playing music. You put them over your head and people leave you alone.
It feels like I shouldn't get so sick of people, like maybe I'm in the wrong for having such a thin-skin and wanting to isolate myself for a few hours after work?
You have just discovered why taverns and coffee shops and pubs and malls exist. "Third places" have declined with the suburbanization of America and the expansion of homes but as we grow more and more unequal, and more and more people are forced to take on roommates, expect to see them expand. Historically, "home" hasn't been this grand place where you could do pilates in the foyer. "Home" is the bedroom where you and your wife and your three kids live. Pubs and taverns are the places you go and pay a rental of 2 beers in order to have a place to sit where you also have room for both elbows to be on the table.
Another option might be something as simple as a membership at 24-hour fitness. Get done with work, spend 20 minutes on a stairclimber, do 3 sets, then hang out in the sauna.