Advice please! Am I pregnant?

Hi ladies, this is my first time posting here. My LMP was 11 august. Tested on 8th September and got my bfp. Booked an early scan for 20th September due to history of recurrent miscarriage. Unfortunately I started to spot bleed and ultrasound showed no pregnancy. Blood test showed low HCG and I then had a period/miscarriage bleeding for 5 days until 25 September. I had a positive opk on 26th September and dtd. Only once. Started to feel pregnancy symptoms on 3rd October (sore boobs, headache, needing to pee). Took a CBD and got Pregnant 2-3. Did two cheap tests with pink dye and got very strong positives. Went for a scan yesterday 4th October and no pregnancy was seen. No evidence of ectopic and lining of the womb was thin so no retained products. They advised me my tests must be faulty as I’m not pregnant! Tested again today and strong line! What is going on??