I would just reply back "no thanks, got it covered." It was either nice or nosy of her to ask. If nice then a polite response is good. If nosy then a polite response is still good because it discloses nothing.

Me: 60 w/ S18, D24, D27

M: 21 years; BD: 06-14-12; S: 09-10-12; D final: 03-17-14; XW:57