Yeah, I think it might be down to what Kenworth said. I was already on the borderline between medium and large for the Abena Abri-Forms and had been using the medium fine for a while. But now that I'm on estrogen routinely I'm getting more fat depositing in the hips than in the belly and it appears that I've outgrown the medium's hip measurement despite actually having lost a good number of pounds. So I'm going to order some larges and see how those work out.
And @ MattyMax, randomly as in time, but the location was generally in the area of the wetness indicators. Would split wherever the buttcrack was at the time.