Could you have ovulated late? I have clotting disorders as well and am currently 27wks pregnant giving myself those daily injections. With this one I tested a couple days before my period was due (day 33 or so) and it was negative. I just figured I wasn't pregnant and my period was late. I had breast tenderness and cramping as well. About 10 days later, still no period and I had a wave of nausea which sent me to the store to test again. That one was positive, called the doctor and started my injections immediately. Are you taking a baby aspirin every day? My reproductive endocrinologist had said to take one daily and when I got pregnant start the shots. I still do both and so far everything is going well. So, give it a few more days and test again, or call your doc if it will make you feel better :) Know you're not alone though, I had 2 early miscarraiges between my 3yr old and this one, which is how I found out about my clotting issues. I wish you the best of luck!