Pregnancy test negative but pregnancy symptoms showing up

Patient: Hello doc, i am 22 year old and have very irregular cycles, my cycle was on 31st july, on 15th sept, i had a sexual contact with my bf, he rubbed his penis on my vagina but dint ejaculate on or near the vagina. to be safe, i took the i-pill within 24hrs of time, i got bleeding which was like a period for two days on 25th september. I took the pregnancy test almost after 1 month that is 20th oct and it showed negative. . however i am having symptoms of pregnancy lately and not got any cycle after that. what are the chances??

Symptoms: Headache, naussea, and more urine bowel passing