+ve test x3 followed by lots of -ve tests but feel really pregnant

Hello, my fiancé and I are not trying to conceive and I've been taking micronor, but have occasionally slipped up. The first day of my last period was the 3rd Oct. I had had a very long day on the 22nd I barely drank and didn't pee until about 930pm. I felt strange and for the past few days had some pregnancy symptoms that I ignored. I had a couple of spare tests (10miu) from a scare I'd had a few months before that was negative. I did the test and it was -ve. The next morning I went to throw it out and saw it was positive. I retested that morning with FMU and it was negative. I spent the whole day nauseous so came home and tested in the evening again and this time within the allotted time it showed positive. Same next day FMU negative evening positive. I then had to travel to San Francisco for work and my hours were all over the place. I tested over there and it was negative (25th) and repeated with different tests all negative. I have had and continue to have today many pregnancy symptoms, nausea, lower groin pain pulling/ sharp pain around my belly button, tiredness, constipation (very unusual for me) bloating (again unusual) +++ flatulance, incredible dizziness where I'd be falling over and feel like I'm bobbing in the sea. I have an appointment on Monday with the GP. My period according to my tracker is due 3rd Nov. I'm driving myself insane trying to find out whether I am or not. Has anyone been in a similar situation? My best friend is pregnant now and I don't want to upset her with this and 2 other friends have had late miscarriages. Many thanks in advance. Plum