Feeling off

I'm currently 12 days late. I had unprotected sex during the third missed day. I know he came inside me. It didn't even occur to me that I was late until after we had sex. My body was already feeling off because I had taken a plan b over a month before, then I had gotten on a new bc a couple of weeks before that. I know plan b is suppose to delay ovulation, so I may have ovulated later than normal. Most of what I've been feeling can be explained by other things. But there are some things that can't. But I feel like it might be too soon to feel anything if I'm pregnant. I'm actually not under any extreme stress. This is the first holiday season were I've barely had any stress. I'm also not sure if I was ovulating already when I took the plan b. I took a pregnancy test 2 weeks after taking the plan b and it was negative. I was also spotting at the time, so I just took it as the plan b worked. But now I'm wondering if the plan b caused a false negative on the test. I haven't really been over thinking it, I've been keeping myself busy with other things to keep me from thinking about it. All this just really occurred to me because I was trying to decide if I should take a test in one more week or two and I was thinking about the things that my body was feeling that I couldn't attribute to something else. I just think it would be to soon to feel those things if I was pregnant from when I had sex during the missed period.