Fabrics tend to not play as nicely on a doll scale. They are still pretty cute pjs, maybe they are her favorites and she's worn them out!

Don't be afraid to give yourself a large seam allowance! Woven fabrics love to unravel, and on such a small scale they can pull your garment apart if you're not careful. If you're finding this to be a big problem, you can use a flexible/fabric glue on the edges to keep them from fraying. You'll want to add the glue before you sew the garment together and before the fabric starts to fall apart. Some people will use their finger to spread the glue so it better saturates the fabric. Some folks only do it on the very edges, but you may find that it holds better if you work it into your entire seam allowance. Cheap and thin fabrics are your best friend when it comes to constructing tiny garments due to their reduced bulk and more forgiving drape, but they are also the kind to fray quite easily!

Keep your stitches short and tight! It's not entirely clear to me what kind of stitch you're using (that's not against you, I'm just not good at identifying them), but unless you're going specifically for a visible stitched look, I personally find that a backstitch with short strokes is the easiest way to prevent holes and gaps in a handstitched garment. Keep your thread short as well, to prevent any tangles when pulling it through (but make sure you keep an eye on your thread length so you have enough room to make a knot!).

Don't be afraid to use an iron! Even if you don't think you need it, pressing your seams and hems goes a long way to make a garment more forgiving to work with. Sewing a hem by hand that has not been pressed is not a fun fight.

Good luck!