How do I tell my chubby girlfriend I like big girls?

I AM NOT LOOKING TO BE A FEEDER! OK, I love this girl, and I DO NOT want to lose her. She isn't huge, but most people would probably describe her as fat 42"-46"-52". She seems comfortable with her weight, but I don't know how she'll react to me saying I like her at the size she is. That being said, I WOULD NEVER FORCE HER TO GAIN/LOSE/MAINTAIN WEIGHT. I JUST WANT TO BE HONEST WITH HER WITHOUT HER THINKING I LOVE HER FOR HER BODY. I call her sexy all the time, but I think she assumes it's playfull. We're both virgins (we're 16) and have been dating for over a year. I've always been attracted to bigger girls, but I love her for her.