I don't normally ask for help on this kind of thing as I'm quite happy in the area, but this one is niggling me. It's the fact they're all related, but commas or dashes seem wrong, and yet I'm not sure full stops are correct either. I must have lost at least nine pounds since leaving home. Whenever that was. I'd long since lost track.
It's not wrong. It's a question of style or flow, and if the above represents what you want, then go with it. Using commas or even dashes wouldn't be wrong, either, it would just give a different flow to the sentences.
Yes, I kept saying it in my head, in the way my brain imagines it being said, and the separate sentences with definate stops between each is how I hear it.
To me, it looks like those should be commas with one full sentence. I must have lost at least nine pounds since leaving home, whenever that was, I'd long since lost track.
It feels stilted to me, but that might be the effect you want. I would go for: I must have lost at least nine pounds since leaving home, whenever that was. I'd long since lost track.
I like Tenderiser's version, but if this is for creative writing I'd accept any of the possibilities mentioned. (Well, except for @doggiedude's - sorry, Dude, but my antipathy to comma splices is as extreme as it is irrational. They make my eyeballs bleed.
I don't know why I'm fine with sentence fragments, multiple dashes, loads of other non-standard grammar... but one damn comma splice? HELL, NO.
I'll chime in, for what it's worth and agree with @Tenderiser and @BayView. I wouldn't bat an eyelash if it were dashes, full stops, or commas. But I definitely think "I must have lost at least nine pounds since leaving home, whenever that was. I'd long since lost track." sounds much more smooth than the other possibilities.
I wasn't taught how to use commas correctly until I was 23ish. The lazy 'use a comma where you pause' non-rule they teach kids has a LOT to answer for.
I stare at the original, and Tenderiser's, and can't make up my mind. The original is technically incorrect. I think that the incorrectness is well within the limits of what's allowed for style, especially in fiction, but it is nevertheless technically incorrect. I don't know what percentage of agents/editors are sticklers about correctness, so I don't know if it would add risk of rejection if it were included in a submitted piece. An agent or editor who doesn't know the writer might be uncertain as to whether they're seeing a style choice or a lack of understanding of technical correctness. Tenderiser's is correct, and it also arguably flows more smoothly and gracefully, and it's just as engaging. But it has a very faintly different mood. The original has as sort of exhausted thought. by. thought. by. thought. mood that Tenderiser's version loses.
Thanks everyone. @Tenderiser - please write an article on the correct use of commas, because even though I feel pretty confident with them these days it's only through instinct that I use them. I don't use them because I know where they should go.