Pregnant but had a period

I am 20 dpo and took a test today. I had a 5 day period though (which is short for me. Mine usually last 8-10 days). I had the same symptoms I did when I found out I was pregnant in April. I also had a 5 day period for that one as well. I am freaking out because every where I read... having a period after ovulation... usually ends as a chemical pregnancy.... the same thing occurring in April. I don't know if I'm just being paranoid... or if I should expect the worse in this situation. I can't even be excited about my positive test because I'm so afraid of losing my baby.