I'm not sure if I would describe Jo as someone with "Self love" so much as "someone who has big boobs and doesn't pretend that she doesn't." Not that Jo doesn't think she's pretty, because she does. :M It's just not the term I would use to describe her, because she's not proud of her figure; I guess she's more indifferent about it.

As for the name-calling, she's heard it a lot in school and just doesn't really care at all about that anymore. She's also used to guys hitting on her. She's not naive, so it's really unlikely for her to fall for a creeper guy in the first place... but Gabe's been overprotective of her since she entered high school. :M
(OH YEAH, THEY'RE SIBLINGS, AREN'T THEY??)

By the way, it's completely possible that Jo is a virgin.