Hello! I'm 18 Years Old, 5' 4" And About 118

Hello! I'm 18 years old, 5' 4" and about 118 pounds (it varies)-I have been worried about this for a few weeks, but the last day of my last period was October 14th and I had unprotected sex the day after (I was pretty much done bleeding anyway) and it's possible my partner didn't pull out in time..I took "plan B" 24 hours afterwards and experienced bleeding ONCE randomly 6 days after (it bled and after I found it I didn't find anymore) and then had the brown discharge afterwards that they say comes after implantation. Is it possible I'm pregnant or is this just a side affect of the pill, because the bleeding was random and my period was totally over. The Brown discharge lasted about 2 days- Now a month later (about) I already expected my period to start alittle over a week ago and it never did and I don't feel the way I usually do when I'm pmsing? I feel consistently bloated, I'm peeing more than usual,and I have fatigue. I have been told I'm moody and emotional and I'm starting to think I'm pregnant. My mother says we have always been "fertile" women and have no problem conceiving (I'm wondering if anything happened it happened between the time before I took the pill). I took pregnancy tests that were negative but I also read that being previously on birth control (tri sprintec) (I was on it about a year and a half ago for about a year) can cause the pregnancy hormone to be too low to detect in some cases. ANY imput would be very helpful because I didn't want to take a pregnancy blood test and be negative I just find that embarrassing after wondering about it so much. It would be great news if there is a possibility- I regret taking the pill... Thanks!!!