Just a heads up that Maryland's PhD in Biostatistics and Biostatistics requires the Math GRE. I think it's probably the only one on your list that does.
I agree with omicrontrabb that boosting your quantitative GRE score would probably help.
You might have luck with Dartmouth's QBS program, they have a slightly larger cohort than some of the other programs you're looking at (like Vanderbilt, Brown, UMass, Drexel which are usually ~4), and have people coming from different backgrounds. I think the general focus of the department is more on epidemiology/bioinformatics than biostatistics though