What Causes Brownish Spotting Without The Actual Periods?

Hello. I need to pick your brain and see if I have cause for concern. I had sex during my fertile week (I track my cycles using an app religiously) in late March and my cycles have been unusual since. in April I was 4 days late and had brown spotting (something I ve never had). I found it odd and brought it up to my OB in May for my annual and also had him test me for STD s. All lab work was normal and my cervix had no polyps .The spotting (now pink) however has come like clockwork 4 days prior to my cycles and they are much lighter and shorter. I ve had 2 children (3 pregnancies total) and 1 c section/1dnc . I m starting to notice odd symtoms that I ve looked up online that many women have experienced in pregnancy. I had a double ear infection for the first time since childhood that has effected my sinuses and sense of smell and taste. Recently I ve noticed that my 7 yr old c section scare has changed in appearance (from flat to rigged), within the past week I ve felt fetal movement like flutters in my lower abdomen multiple times in the same area, and when I sneeze lately I ve been having round ligament pain which I remember all to well and is unmistakeable. I ve taken a couple of hpts and they ve been negative . I have also noticed bleeding gums when I brush my teeth, and my remnants of my linea negra seems to also be darker and longer. I have really good insurance and I can go to my doctor but it s kind of taboo for women still having a cycle and wanting a blood test/ultrasound. I m really concerned because if I am indeed pregnant I d be 15 weeks and I haven t had prenatal care. Have you come across pregnant women who still have their menses and what s the best way to approach my physician?