The first such thread is that Liz feels as if she's just this big nobody who's lost in the crowd and no one wants to notice her because she's too homely to be loved. If she could look better, she'd be loved and cared for and she wouldn't die alone and forgotten because she's always on some level going to be a freaked-out twelve year old girl who thinks that every day is always Doomsday.
The second thread is that her parents aren't very much help at all. She's caught between the Scylla of Elly's active hypocrisy and the Charybdis of John taking her bad mood as a personal affront so is left rudderless because Mommy talks about smiling and not worrying about her looks but never smiles and frets about her appearance and all Daddy says is to think about the refugees in war zones dying of world diseases before she talks about something useless like problem hair or that fucking pile of junk the moronic dildo shoved in her mouth because he thought a coping mechanism was a plot to ruin him.
Finally, we have Mike delighting in making things worse because the spastic little gremlin is always going to have it in his stupid bloody head that she should feel bad for being born and destroying his life. He can't resist the overweening temptation to subvert any attempt to make her feel good because she doesn't deserve happiness because he has to act like he's an adult to be treated like one and kids on television fight like scorpions anyway.
The only real change is the addition of a new reason for to feel useless and unloved and unnecessary: April. I'll remind you why she's a rant-inducing slight waiting to happen next time.