Love and sex

Long story short I need information on this?? My bf and I had sex on the 13th of December. then on the 14 I had bleeding for three days so idk if it was my period cause usually it lasts for 7 days not 3. So I could be pregnant or not but my question is if I do get my period in January but had sex again on the 30 31 and the 1 could I possibly be pregnant with that time around instead of the 13th time ?? Sorry if this don’t make sense I’m just confused and need help to understand. No mean comments.