Don't know what to think?

So I have been getting faint positives since 10 dpo , we'll at 14dpo went to the dr they did a blood test and said it was negative , but said I had a cyst on my ultrasound and had to go on bcp, so for the past 2 weeks I have been on them and quit testing when Dr said blood work was negative , we'll now I have been experiences some cramping and thought I was ovulating so i had 4 positive ovulation test thought that was weird so I randomly took a pregnancy test 2 weeks after dr said my blood work was negative . My question is if I'm pregnant why wouldn't my blood be positive and if I'm not why do I continue to get faint positives . Any advice would be great as Re wants me to start femera in 2 days