Irregular periods

So in October. I had gotten my period on the 3rd. And got off on the 8th. Around that time. My husband and I had sex but the condom broke. And the next day I took the emergency contraception pill. Everything was ok. Until I got my period again on the 18th. On the same month. I don't usually get two periods. I just a baby 7 months ago. And nothing like that has happened to me before. Now it's November. And I haven't had my period yet. I took a pregnancy test. And it tested negative. I don't know what this could mean. Could I be pregnant? Has this happened to anyone before?