With your background in design, getting into an ID masters program would likely not be a problem. There has been much discussion here on the pros and cons of ID masters. Many tend to be more theoretical. This is more of an issue when candidates come from non design backgrounds. Some masters programs offer a three year path where you can spend most of your first year taking ID undergrad skills classes.
Short answer is it is doable. It is more about spending some time to find the right program. I highly recommend visiting schools if you can. Also, I know some friends who did masters who benefited from working for a couple of years in between undergrad and grad programs.