Unprotected sex on the pill, 6 days late w/ light brown disc

I've been on birth control for about a year straight now. I stopped taking it December 19th and had a very light, watery period. Normally I am incredibly heavy and it lasts for days but this time it was only three days of watery bright-red blood. I'd gone off birth control twice before for medical reasons and had another period a week after my normal one and then went back to a four week cycle.

I started getting really nauseaus (even vomited a couple of times and I NEVER vomit) and fatigued shortly after the bleeding stopped. I had missed a number of pills in my December pack and started thinking I could be pregnant. I have many of the symptoms and even got heartburn for the first time in my life the other day.

I've taken three pregnancy tests. I took one four days before my missed period with an early response. I took another the day after and it came back negative again. I took another test yesterday morning and it had a very very faint line before the control line appeared. It faded as the control darkened and then the control line bled into the whole window. I'm now 6 days late and for the past three have been getting a light brown mucousy discharge when I go to the bathroom. It isn't a lot or everytime. I'm not sure what to do anymore and would love any advice.