TMI/GRAPHIC PICTURE: spotting or light period?

Hi ladies, **i apologize for the long explanation ahead but I'm very paranoid and I just need help**.      I'm 18 and I'm really not hoping to be pregnant. However I'm extremely concerned because my period (according to glow) is due tomorrow (Monday, 4/10) but I started light bleeding yesterday, (Saturday, 4/8). Usually I have a pretty regular period meaning my cycle lasts between 28-30 days. The last 2 times I had (protected) sex with my boyfriend was recently last Thursday (4/6) and then Friday (3/31). So anyways we always check the condom for any breakage afterwards and it never broke. However I'm just paranoid and a bit obsessed I think with feeling like I'm having implantation bleeding and I'm trying to calm down because I know I may just be overreacting. But this bleeding that I'm having is lighter than normal and usually when I start my period it's pretty medium-heavy (in quantity) the first few days and it soaks the pad. I'm having very slight cramps and  it's not enough to be the type of pain I usually feel from my period. I attached an image of the pad I just recently changed because I'm confused on whether it's "spotting"/IB or just a light flow for whatever reason. (Oh- and I'm not on birth control but I did take plan b about 2 months ago so I have no idea if it's a late side affect which I'm pretty sure it's not but I'm justaying down all the background information that could possibly help) Thanks so much for your help in advance ❤️