Any insight pls

End of November I unprotected sex right after getting off my period (day or two after) for a just few seconds before grabbing condom. He didn’t finish prior to grabbing the condom. I took plan b a few days later (out of the window but I just had to make myself feel better) next day had heavy bleeding and clots like on bad period days. That bleeding lasted almost a week. Just like my periods. So far I haven’t gotten my period this month. I took a pregnancy test a few days ago and it was negative. Does anyone have any insight? Obviously there is a chance I could be bc I had unprotected sex, but how likely for just a few seconds and the fact he didn’t finish yet? Just wondering if the plan be messing up my cycle this month as well?