TTC #2 after baby with anencephaly

Okay so on April 1st my husband and I had a baby boy at 21 weeks due to the birth defect anencephaly. We started to try again right away once the dr released us. My first period after our son lasted almost two weeks . I did track it with this app and now the app says I should start tomorrow but yet I still haven't had any signs of AF. Just wondering if I could be pregnant or is my cycle still messed up?