not sure what's going on with my body!!

My husband and I want a child but also we weren't trying to have one. I had missed some of my pills last month and I started really late and my period was only 2 days but also it was brown blood not red or pink and VERY LIGHT. I was too scared that I might be pregnant and bought a test and took one right after I got off my period and it said negative but I haven't been on my pills since because I don't want to be taking them if there's any possibility.