Unsympathetic heroine because she acts like a perpetually whiny 4 year old. She winds up pregnant because she was trying to be a "bad" girl just to get back at her parents. She hates her dad for having an affair (with their dentist) and her mom for being a corporate attorney instead of a mom (and for taking dad back).
Now that she is pregnant she refuses to take any responsibility or consider her potential courses of action (abort, keep, adoption). She won't interact with her parents, her aunt, her BFF, the father of the baby, Planned Parenthood rep, potential adoption candidates, etc. She gives them the silent treatment, just sitting there like a lump, refusing to speak or email. She occasionally tells herself she should do something but makes excuses for why she never follows through.
Her martyr act ("oh woe is me, my parents suck, my life is over, I'll never amount to anything so nothing matters") gets old quickly. This isn't the 1950's, teens get pregnant today without the societal censure they faced back then. Everything was too self-inflicted for me to develop any sympathy for her.