Periods Problem. Contraseptive period.

Hello Doctor, I have a history of PCOS and my menstrual cycles are irregular. I had unprotected intercourse multiple times on July 4 and July 5. My expected period was around July 7, previously it was on 7th June. On Tuesday night(7th july, 7pm), I noticed what seemed like the start of my period. While urinating, I saw a thin thread-like streak of blood, and I thought my period had started. However, since then, I have had no further bleeding at all, only my usual vaginal discharge. There has been no spotting, no flow, and no blood while wiping. I'm concerned because I don't know whether this was the start of my period, implantation bleeding, or just hormonal spotting related to PCOS. I would like to know if this is normal, whether I should wait for my period to start properly, or if I need a pregnancy test or any other evaluation or take a contraseptive pill cause I'm in my 5 days of contraseptive period. Thank you.