Confused & unsure

Hi everyone! I'm really struggling with a lot of insecurity! I've actually been off the pill for 2 months now because we want to start trying for a baby. There's no pressure on us to conceive right away; we're happy to wait, especially since we've just bought a house and are still partly renovating. Here's the thing: in my first month off the pill, I had a 27-day cycle, so I'm basing my calculations on that. According to that, my period should have arrived around August 2nd in my second month off the pill. A week before that, on July 27th, I started getting light pink spotting and some lower back pain. I thought my period was coming, but it wasn't.. I had this kind of spotting (a few drops a day with some mucus) until August 1st, and then it stopped completely.. I'm also feeling nauseous and throwing up regularly, especially from after dinner until I crawl into bed. My breasts feel fuller, and I can clearly see a whole network of veins (which I never have normally). Sometimes I get a slight sting in my nipples, and I still have some mild lower back pain.. I thought I might already be pregnant since I haven't had my period yet. If I continue with my previous 27-day cycle, I should be 4 days late now, so I did a home urine test, but it was negative.. I'm worried because I have a throbbing pain in my left ovary area.. Looking at all the symptoms, I really feel like I might be pregnant, but with the negative test, I'm really scared of an ectopic pregnancy. Does anyone have advice for me or has anyone experienced this themselves! I feel so insecure!

Best wishes