I’m in a bind!
I’m swatching for the Belle Epoque, and a 4mm needle gives me the right row count, but 3.5 more in the stitch count, and a 4.5mm needle gives me the right stitch count, but comes up short by 8 rows on the row count.
Which do I use?
Correct stitch count is what you’re after.
You can always add more rows while knitting, but you can’t go back and add more stitches to every row. 
Try blocking to adjust: you may find that you can block stitch count wider without affecting row count, or row count higher without affecting stitch count. But you can use row number also to figure out what the vertical measurements were meant to be and knit to that.
Sarah
Thank you!
Redwitch, unfortunately blocking to fit won’t work, as I’m using a silk/viscose blend…
Will cast on today… it’s my first sweater… WOO!!!