HELP!!!! MEEE!!! PLEASE

So my period ended January 30th and I had sex on February 1st which was 7 days ago. We used condoms and I’m on birth control but I haven’t been taking it consistently. Yesterday I had went to the bathroom and I seen Brown Discharge & The same thing today. I took a pregnancy test it came up negative and I doubled up on my birth control last night. I took 4 at once.

I’m scared I don’t know if this is implantation bleeding because my period isn’t due until 16 days from now!!!!