Alright, well I was/am in the same exact situation as you are in - except my undergraduate degree is in vocal performance. Basically I had wanted to further my classical training in voice as well as study architecture, and focusing on voice first was the better option at the time. But I am now graduating and have already been accepted into 4 MArch programs, and so it's definitely possible. I have spent the past four years working toward a major in Graphic Design as well, and thus have taken plenty of art courses that have provided me with more than enough work for a portfolio. The only school that I applied to that you are looking at is Pratt, and I haven't heard back from them yet. But I've been accepted at North Carolina State University, SCAD, Arizona State University, and Syracuse University. Denied at Parsons and Illinois Institute of Technology, and waiting to hear back from Pratt and RISD. Hope this brings encouragement and confidence, and if you have any questions, let me know!