Period lateness


So I was suppose to start my period 2 days ago and I’ve been on the pill for about 4 years now. My period hasn’t come and I checked my cervical position to see if it was low or high and it’s kinda high and hard but when I was done checking there was a little bit of brown discharge (like the kind I get the first day of my period) but other than that no blood. I haven’t seen my boyfriend since November 17th and I had my period right before then. I’m like 95% sure I’m not pregnant but I don’t know what else could delay my period? Any thoughts?