Birth control Loestrin 24?

I started taking the birthcontrol, Loestrin 24, about a year ago. I had my period at the end of every pack for the first 6 months and then all of the sudden I missed a period. Thinking I may have been pregnant (since this had never happened to me before) I stopped taking it. 2 months later I finally had a period so at the end of that cycle I started the pill back up again. I started taking it again in July and at the end of the pack I didn't have a period. I started the next pack (that was about 2 weeks ago) and yesterday I started bleeding a little. It was a very small amount and it didn't look like normal period blood. I'm not due to have a period for another 2 weeks. What do you think caused this? Was it just breakthrough bleeding? Has anyone ever taken Loestrin and had these problems? Thanks!