Still having somewhat faint positive bfp?

As an update to a question that I asked a few days ago, I am due for AF tomorrow, but since sunday have been getting faint positives on FRER (whether I use FMU or not), My question is shouldn't by now they be darker? My BBs are little sore once in a while, I do have some periods of nausea, but I have also been cramping on and off all week (each day getting a little less). I am so afraid that this is a chemical pregnancy. My plan is to call my OB on Monday for a blood test. I am just wondering what everyone thinks? I am also afraid that like many months, my mind is feeling things that really aren't there.