Worried!!! HOLY SHITTTT

Last Monday, my bf and I had unprotected sex. It was my first time as well as his. He pulled out before he came but we got worried about his precum. The next couple of nights, I felt constipated. I was cramping a little bit. Then Thursday morning when i went to use the bathroom there was light bleeding in the toilet and i got extremely lightheaded and dizzy. I’ve been bloated and i dont have as much as an appetite as i used to. My period is supposed to start next Tuesday which will be about two weeks after the sex. Should i take a test or is it even possible that i’m pregnant?

So on tuesday of this week i took a PT and it came out negative. This morning (around 3-4am) i had a lil itch down there so i reached down to scratch and came back up w blood on my finger. My period is supposed to come on tuesday so i thought it mighg be that. But this morning i looked at my pad and saw this:

Is that implantation bleeding? Normally when my period comes on there is no spotting or anything beforehand so i’m really worried and i really need some help.