I’ve commonly heard it said that Amy is a flimsy character because she changed jobs often, and that just makes me shake my head because…
The first thing we learn about Amy right out of the gate, her most defining characteristic, is that she’s a free spirit. She kept her original accent after years of living in an English village, she witnessed a mysterious event as a child and no one in the village could convince her otherwise even when they started treating it as a problem. She’s the sort of person who would keep insisting that 2+2 is 4 even if a totalitarian government told you it’s 5, which is really admirable in itself.
However, like most traits, this can be good or bad depending on the circumstance. People who want to be free are often afraid of being tied down. The whole plot of series 5 was that she was reluctant to fully commit to a perfectly fine guy that she ostensibly really liked, and like downplaying that whole relationship… in this context it was certainly a character flaw that could’ve cost her much if Rory hadn’t chosen to forgive her, which he didn’t have to. (which is good like… many of us have hangups or make mistakes. I certainly have. )
(Though it was nice to see a scenario for once where the girl is the emotionally constipated one with the commitment issues and the boy is the gentle, patient person who wants a family, like in a lot of media not only do you always see the opposite it’s treated as inherently indistinguishable from boy/girl; both are valid, real, common personality types, but any gender can have them.)
In the mbti and enneagram respectively, I’d class Amy as an ESFP 7.
And just like these free spirit sorts of ppl might be reluctant to stick with one particular partner they might also commonly change jobs, try a new one when they get bored of the last. This isn’t necessarily a bad thing as it makes you flexible & a jack of all trades. That she doesn’t stick with a job too long is itself characterization, in the same way as someone having skills from doing the same job a long time. (meanwhile Rory, the down to earth reliable one, stays a nurse the whole time) I mean some ppl can’t have the same job from 20 to 60 because they get fired & have to take what they get. This is something people absolutely do in real life.
The kissogram thing is exactly the sort of mildly socially transgressive job a free spirit would have and is also a result of that phase in her life where she wanted to put childish things behind. (something I find super relatable tbh), the model thing is kinda similar, making money of her looks, it doesn’t require deep thought if it’s just a short-term gig.
Then as she gets older & wiser & gets to know herself better she ends up with stuff that utilizes her actual talents & inclinations more like the journalist job.
The “defining” job for Amy, in the way that Rose is defined as a retail worker, Donna as a secretary, Martha as a physician, Clara as a teacher (or the Doctor as a scientist, for that matter) etc. is not the first one she had when she was young & didn’t have her life figured out, but the one she eventually ends up with: Author. I think I don’t need to elaborate how her whole arc & presence in the show had a big storytelling motif going on from start to finish.
Interestingly enough Clara is seen owning books by Amy, and she also went to meet some of her favorite authors so it’s possible that she said one day, “I want to meet Amelia Williams!” Cue sad explanation for why that’s not possible.