Background checks

Hey guys, I only have about 3 weeks of school left and I'm getting ready to send in the NCLEX aplication. Our instructor informed us that if we had any felony or misdemeanor conviction to put it on the app even if it happened when you were a minor. Well, I got into some trouble over 20 years ago and spent 6 months in a boys detention center. I was a minor at the time. I don't remember if it was a felony or mis. I'm thinking it was a felony because it was technically a B&E I think. A kid I knew called me up and said he was house sitting. I believed him and we drank some soft drinks and stuff. I was on probation at the time for underage drinking is why I think I got sent away. I called the courthouse where I went and they said all those records are expunged, with no records.
I've got 3 years and major debt into nursing, now in the last month I find out this might be a proble! My question is what do I put down? Just as I've explained it above? I don't really remember and neither do my parents. Now I here even if they let me take the test and get licenced, I may not get hired if there is a felony on my record (even as a juvenile).