"I felt kind of unclear about how Annie even afforded the coach seat."
She took back her rent check and bought the planet ticket. One can easily assume that she justified it, because the roommate's sister was living there rent-free.
Yeah, it's not clear, but you have to read between the lines.
"And the fact that the main character's biggest ambition is to bake cupcakes."
That sentence sounds incredibly judgmental. Or I'm just misreading it.
And I didn't get that she was saved by a man at the end of the movie. There's no guarantee that they're going to last. And there is no guarantee that Annie will be happy, single or with someone. Her romance with the cop was a subplot. The movie was about her depression during a time when her best friend was moving on with her life.
At least, that's what I got out of it.