Missed my period, but I’m on the pill!!

I’ve been on the pill for 6 years. Always get my period every month. I am sexually active and have unprotected sex but I take my pills every night no problem. Until now, I missed my period. I took a digital early detection test and it says not pregnant. I have the 24 active pills, and I usually get my period on day 3 of my placebo. I’m on a brand new pack now. So it has been 2-3 days late tbh.

We had sex last night and I wiped and it was red/pink blood, and that was only once. Never bled after that. I’ve been stressed also lately and been taking this allergy pills montelukast.

What do u think? pregnancy or just stress or just side effects of me being on the pill for this long??