From The Baby Book by William and Martha Sears:
"Baby's speech explodes from an average of ten words at fifteen months to as many as fifty words by twenty-four months, though many sounds are still unintelligible except to parents."
I have added a list of the signs Annabelle does and the words she says. Some of the words she says are ones only we can understand. You can see that she does about 30 signs and 20 words. That's a vocabulary of 50 words at 13 months! You're impressed aren't you!
I will try to update the word/sign lists as much as possible. It's fun to track what she is doing. I probably even forgot some!