It should be an increase of 4sts each in rows 2 and 4 and 6sts each in rows 6 and 8 so if you're making the smaller size, that's 51sts. The increases near the markers are shaping the toe. You could look and see if you can tell where the extra sts are although this may not be so obvious in garter stitch. Depending on how many extra stitches you have, make sure you're only doing 8 rows and haven't put in an extra row. If it's only one or two extra, leave out the kfb at either end of the last row and continue on.
You can check the kfb
and backward loop
increases if you need just to make sure you aren't somehow adding an extra loop.
It's a very sweet pattern. Congratulations on the baby!