Board Thread:The Reference Desk/@comment-74.106.61.93-20130224211810/@comment-188432-20130225000743

The 13 thing is easily countered with other quotes which suggest 13 ain't the limit. It's at best a theory of how many regens a "proper" Time Lord has.

And of course, River isn't a "proper" Time Lord. We don't know what she is, and it's a bit hard to understand how she's really Time Lord at all. She's humanplus, not so much half Time Lord. So whatever number of regens she had is unlikely to be the number the Doctor has.