No periods

I've been on birth control for over a year now since June 2016. I would either get a period once a month or every two. In march 2017 I missed two pills because I forgot and didn't have a period until may. It was a very heavy period. I then took my pills pretty religiously. Maybe one time I took it in the evening instead of morning. Then June 25 I got a really light period for a few days. I got sick in August with an bacterial infection and I took a pregnancy test that came back negative. Due to my infection, the antibiotics could effect my bc. But we had sex at the end of me taking it but we used a condom with spermicide. I then got cramps, discomfort and mood swings September 15th and 16th. The blood was brown and barely even covered a painty liner. We had sex about a week before. Am I being paranoid about being pregnant is this stuff normal? I've also been stressed because I just moved and also I am in College. Anyone's periods just stop after being on birth control for a long time? I'm on Lo Loestrin Fe