A BFN with a positive end

I took a pregnancy test few days before my period was due and to my disappointment it was again negative. It was only the third month trying but it really hurt me because we BD all the critical days that month and I was hoping for a BFP. I never ever believed I would ever be so lucky to have a negative eventually turn into a positive, but over the next few days, as AF wasn't showing up, it eventually turned into a faint positive and then a stronger one. Had my first blood test yesterday which was 667. Not low, but I expected it much higher. I am having another one tomorrow to see if it has doubled. With my son the first time it was 1700. I went about the same time as I did now but this time ovulation happened on day 17 whereas with my son it happened day  13 or so. Had a truly horrible MC before my son so I am trying to keep it to my self for now and see how it goes. good luck to all the ladies out there! Baby dust to those TTC and healthy 9 months to those already pregnant!