False negatives?

I had a miscarriage on Feb 18th and didn't get my next period until April 10th. That was a pretty big gap, so I have no idea if my cycle is back to normal or still wonky but I had ewcm the very beginning of this month, so I think I may have ovulated around that time, but have no other ways of knowing besides for the cm. We had sex on the 5th, so it's been 16 days now. I took a new choice (one dollar) test on May 17 and May 20, both negative. Today and yesterday I've been having feelings in my lower abdomen (not quite cramps) and started very light brown spotting today. Is it still possible I could be pregnant? Did anyone take longer to get their bfp?