When should I test?

Hi all. About a month ago I posted about spotting before my period. I took a pregnancy test and even though faint, it was positive. I was very happy and so was my husband. For 2 days I was being careful and trying to eat good.... The next day my period started. I read that it is possible to be pregnant and get a period. Many people commented that. So I waited to test myself again after my period and it was negative. I had gone through pregnancy symptoms for almost 2 weeks before I had done the first test so even though it wasnt long, it hurt to know that the pregnancy didnt hold. Ever since my c-section and 1 full year of breastfeeding, my periods have not been regular. I have been tracking the days and thought I was finally back on track since last 2 periods were 28 days which is what i used to be before my first child. Well, if following the 28 days, I'm 2-3 days late. I have never started on the day this app said i would but a few days before it. I do log when my periods start on here. We do want another baby but i am afraid to test early again since the app says i start tomorrow even though its never been right. I dont know how long to wait to test since its driving me crazy. I have depression so Im worried and tend to always get my hopes up. Ugh, I want to pull my hair and scream!