missed period + brown discharge

I had unprotected sex with my boyfriend in November didn’t get my period in December but got it in January. I also took pregnancy tests in December and beginning of January and all negative . I had protected sex in January but missed my period February and now missed my March period. I then took 4 pregnancy tests (different times) without having in inter course between February and March and all negative . I’ve been experiencing brown discharge only when i wipe . I put in a tampon thinking my cycle will come when i took it out it seemed like the beginning of my cycle but nothing yet . My cycle still didn’t start. PS: I’m irregular. Could I be pregnant ?