Confused about whether I'm pregnant or not--

My periods have come on different days in the past 4 months but they've come. They came on the 12th,15th,19th and 23rd ...

So I'm not sure what date would be my missed period. Nearly done with June, I just had brown spotting some days earlier

But ..idk. I'm just confused. I don't feel any symptoms but when I was pregnant with my first. I didn't know I was carrying him until 8 weeks bc I experienced 0 symptoms( no sickness or fatigue ect) and I tested at a hospital.

I last had sex on the 12th where my be released in me. I took a dollar tree test 12 days after sex and it was negative.

Given all I stated, am I not pregnant?

Or do I need more time? The whole ovulation stuff confuses me. So.. I'm just in the dark right now lol