I have a background check at Nordstrom?

I have no criminal anything - AT ALL...but I did leave out the fact that I went to college for a year because I didn't want them to think I was leaving after only a few months to go back. I also left out other job experience because I didn't want to list every last job I've had, especially since the ones I didn't list were really short (like two months or less). Will they be able to see this, and will this count against me? I just really didn't want trivial things like that to keep me from the job, but it looks like trivial things like that will keep me from it because I didn't list them.