Here's a rule I go by when it comes to anime girls: If she's got at least one foot of length between the top of her waist and the bottom of her chest, it's alright to be attracted to her. I wouldn't likely go below 8.
And besides, camel-toe doesn't mean she's fat, she just has a big... "girlhood".
When it comes to REAL girls, I wouldn't go below 15. That's because I'm 16. If I were 21, I wouldn't go below 18 with real girls.