This is becoming stressful

Hello everyone. I need help with solving this dreadful situation I’m going through. I’m not sure if I’m pregnant or not. I had my last menstrual December the 5th 2017, an I ovulated around the 18th to 23rd. Me an my boyfriend had intercourse the 18th an 19th, I had some cramping and spotting of blood either the 21st or 22nd, idk if that was implantation bleeding, only lasted for a few hours not even a whole day. Looking forward to my period January the 5th but it came on the 6th which is odd cause it came on the 5th in November an December, then it came on light an practically spotting the whole first day it came on. The next day which was my second day of my menstrual and the blood was moderate flowing normal. By the 3rd day it went back to light spotting an was like that for another extra day. My periods normally comes on light then get heavy on the first day an last up to 5 days, I keep taking a pregnancy test and it’s saying negative but I’m getting pregnancy symptoms I calculated how far along I will be an I will be 5 weeks 4 days idk if iam pregnant that’s fine if iam but these pregnancy test not working by telling me, I never been through this in none of my pregnancy’s.