How old are you? I'm 20 but I feel the same way. It's been this way since High School - one starts changing and perhaps hiding their new ways (which may be stepped in things they "shouldn't be doing") inadvertently developing split personalities of sorts, until you stop and say "damn, what the fuck is happening and where do this go wrong?". Then you write something like you wrote.
Well, I suffered through HS with a lot of little family bumps and bang ups, with some of the same quotes ("my family understands me the least", happy vs condescending, pointing the finger at my upbringing etc). I mean quite honestly the sight of my mom on a weekday - just her COMING THROUGH THE DOOR - stresses me the fuck out preemptively. It puts a damper on my energy. I think it's warranted because 9/10 times the shit she says is annoying with a tone of voice I've just come to cringe at.
I dare say I'm on the verge of being a grown man and honestly, try as she might, my mom can't really tell me shit like she used to. And she knows it, which is nice. It took her a while, but we're beginning to see eye to eye, or at least, in the middle ground.
As soon as summer rolled around, because I knew I would be living at home again, I decided to start being honest. Told her all the things I do - smoke pot, get drunk, stay out late as fuck blah blah blah. This is NYC and her tendency would be to flip a shit - but I guess the integrity of my honesty, and the fact that we talked about all of this formally, seriously, and I got to just be myself, commanded a little respect in her eyes. I started speaking my mind - with respect, of course - and not letting old notions of self stifle new ones. Kind of just letting them blend.
It's better now but I still feel we have grown apart. While I'd love to continue beating myself up about it, I've come to see my mother a little more objectively (being grown up) and have come to realize that a large part of the disconnect is on my mothers side. She refuses to, or maybe simply cannot, see me as anything other than her little boy. I know she cares about the grown-up things I'm into, but my moms world view is decidedly more simplistic and she's not keen to stay on top of cutting edge things. There is a generation gap, a belief gap (mom is catholic, I'm an atheist), and a quite particular set of sociological circumstances (she was raised by a single mom, I was raised by a single mom, as a single child) that all compound for what is sadly not the most ideal mother-son relationship.
Maybe my situation is different. I love my mom so much, respect her so deeply, and would do anything for her. But living at home for more than a week is fucking torture - and I realize now this is because I am an autonomous human being who simply has developed a set of beliefs and a modus operandi generally incompatible with my mom. I look at my friends and sometimes they are able to work - but its a different set of circumstances, different people.
Perhaps, like me, you just need to get away from the nest.