She is only 5'2". From the video of her sitting - one of the few times in the last couple years we have seen her unedited - I would put her over 400, and wouldn't be shocked if she was closer to 450.
She's always been about 100 pounds heavier than she reports. She was over 300 when she launched with Milk as 220 pounds; she was definitely near or at 400 when she had that "Fit, Healthy, 300 Pounds!" article in Shape. And since she's larger now than she was for that article - and since she is still claiming 300 - she is most assuredly somewhere in the 400s.