Doubtful, but possible pregnancy?

[bcc76]

While I'm sure I'm not pregnant, something just seems off this month.  Wondering if anyone has experienced something similar?
My periods are not regular, ranging anywhere from 25-28 days.  My lmp was on 11/8/16 and I had sex on 11/17 and 11/18.  I noticed cramping which felt like menstrual cramps around 11/24, which is really early for me.  Usually the cramps start the day before I get my period.
My breasts were a little more sore than usual, but not horrible.  Again though, that started way earlier.  I started getting weird nausea around the same time.  But it's not consistent.  Seems to happen randomly.
Finally on 12/3, I got my period...I think.  It's way lighter than normal but heavier than what I've read about implantation bleeding.  I took a test 12/4 and it was negative, but something still just feels off.
Is it possible that I could be pregnant?  Should I wait a few days and test again?

Thanks for any insight?

[Weakatheart]

I'm in the same boat. Had what I think was implantation bleeding on 11-18 it lasted for five days. Very light. Usually only blood when I wiped. I went to the ER the day it stopped thinking they would give me a blood test- they didn't. They gave me a hpt wish I knew would be negative. I had times where I would also throw up. Woke up ate then throw up for no reason. I took three HPT on my own but all were negative. I tought about giving up- I'm not pregnant. But then I noticed my next period isn't due for another 12 days. So I'm gonna wait it out and see what happens. I, too, know something isn't right.