The only reason I think there has been any speculation in this regard is that the mother also emphatically stated that there was 'blood everywhere' and the water was 'full of blood' (i'm misquoting, but its the general gist, and I really don't care that much). Now the thing that strikes me is the report I read stated it was the park's (female) medical staff (nurse\paramedic\first aid) that suggested it could have been her period.
Now - I know there aren't many on the boards here, but i've spoken to some ACTUAL females ( 😮 ) who are medical professionals, and their first thoughts on this were that for the amount of blood present to be mistaken for a menstrual cycle calls into question the actual amount of bleeding.
Yes, the injury is a terrible, regrettable injury. I can't imagine the pain involved, both in the incident and the resulting recovery - but the many details we've seen\read about this injury are, at least, inflammatory. By all accounts now, I accept this isn't necessarily an uncommon injury, but the contradictions and inflammatory language irks me. that's all.