It's hard to tell from the photo's

But it does look like she's got that tell-tale diagonal line down her side.
You've still got a couple of days before she reaches the 120 day count

Some questions...
Is she a gilt ?
If yes, then it definitely looks like the vessel's starting to fill.
Did the boar remain with her after the 24th ?
If yes, he might have caught her 3 weeks later.
DId you see her return to season 3 weeks after service ? (again, as above)
Is her vulva 'puffy' or does it look completely normal ?
It'll start to puff up in the last week or so before she farrows.
HTH
Karen