Needing some advice

So one app is telling me I’m 5 days late one app is telling me I’m 1 day late? I’m very confused I tested 4 days ago with a cheap 4 dollar test from family dollar and it was negative? Should I not worry? I need advice. I had a baby 4 months ago and I had my first period a month ago. I know my period could be messed up but I did have unprotected sex 3 weeks ago when I was ovulating. Just trying to figure things out.