Rebecca,
Like you we potty train early at my house too! I think it is a cultural thing. I've met people from Iran, Uzbekistan & Tibetian China who all potty train their youngsters before they are a year old. I'm the weird one for "waiting"... haha... and my American friends think I am crazy or "it's just my kids" like my kiddos have some supernatural ability/desire to not sit in their own waste... haha...
We began potty training my DD at 16m and DS at 18m. Both were fully trained by 2 - my little man did have an accident last night, but they are rare.
Keep up the hard work and congrats on not having to wipe a bum!