Please tell me that I'm crazy!

So I had protected sex on Dec 13th and we believe the condom worked perfectly. No rips or tears or anything. I had a heavier period starting Jan 3rd but it ended Jan 6th, which is a little shorter than usual for me. I am on birth control but have missed a few doses. I took a pregnancy test at what would have been 5 weeks but I think the urine was diluted and it came back negative. I am having weird upper abdominal pain and diarrhea but it's probably from the stress and anxiety I've caused myself. My cervix feels kind of high and soft at the tip but firm toward the back. Cervical mucus is more watery but I've heard that can happen more on the combination pill. Should I not worry so much or should I take another pregnancy test?