I'm needing help please ladies

My periods was regular before last month (September) it went to 31 days and lasted for 10 days I did have unprotected sex after that period, now I'm late for my periods and it's over 3 days if I follow my 28 days cycle it's 2 days if I follow my 31 days cycle, my cervix is high I can't feel the top of it don't know if it's soft and closed or soft and open even when I have sex like tonight I'm usually sore that time of the month when it's due but it wasn't my partner was all in and my cervix is tilted backwards it's never like this before my periods come I have done pregnancy test it's all come back negative 😢😢😢😢😢😢 what can it be please?