Tax Question: Would I be considered a fifth-year senior?

I’m trying to determine whether or not I’m eligible for the American Opportunity Tax Credit for being a full-time student in 2013. Here is the eligibility criteria:

“For the American opportunity tax credit, an eligible student is a student who: (1) is enrolled in a program leading toward a degree, certificate or other recognized post-secondary educational credential; (2) has not completed the first four years of post-secondary education as of the beginning of the taxable year; (3) for at least one academic period is carrying at least ½ of the normal full-time work load for the course of study the student is pursuing; and (4) has not been convicted of a felony drug offense.”

It’s #2 that I’m confused about. I started college in Fall of 2008 in the nursing program (Associate’s degree). I then took Spring of 2009 off. I went back to the nursing program in Fall of 2009 and Spring of 2010. In Fall 2010, I changed my major and took a semester off. I returned in Spring 2011 as an Associate of Arts student before transferring to a four-year degree in a Bachelor of Arts program from Fall of 2011 through Fall of 2013, when I graduated.

So, I have to have not completed four years of post-secondary education, but did I? With the skipped semesters, I’m not sure if that would be considered completing all four years. I’m pretty sure it means that I can only get this credit for four tax years. However, I have no clue how many years I got it. How can I find out? Will they be able to tell at H&R Block or do I need to find out through the IRS?