My rainbow is 5 months old. After I had him I got on the pill. My period was supposed to start…

My rainbow is 5 months old. After I had him I got on the pill. My period was supposed to start Monday and didn't. So on a whim I took a pregnancy test today. Wth. I am indeed pregnant. And freaked out! Shocked as we didn't want anymore hence the pill which has never failed me. Plus I'm 38. I'm spinning with thoughts. Scared.