Hard to know because mares can be tricky, but since she's started filling her udder, I would expect her to continue and do more filling. She looks like she's elongating, but staying pretty tight, so I think she'll take a little longer for you.
Can you get us 2 good pictures please. One standing right behind her looking forward so we can see how baby is laying, and one full side view right down at her level. This will help us see the positioning of that precious little one and give us some good clues, hopefully.