I took a blood pregnancy test this Sunday. Today is Monday. My cycles are usually 28 days but can run as long as 31. Now I'm trying to get pregnant. My period is due this coming Wednesday (28 days)-Friday (30 days). The Sunday blood pregnancy test came back negative... but I started spotting on Sunday evening. I NEVER spot. EVER. Now I have light cramping. Just a few specs in my underwear and only occasional, barely perceptible, discoloration when I wipe.

Could it be that the blood pregnancy test showed negative because the fertilized egg had not yet implanted and that I could still be pregnant?

My last period started Sept 17. It is due between Oct. 15-17. Is it possible that the egg implanted so close to my period? I am NEVER this early and NEVER spot.

Periods do not always follow the same pattern, so it is not unusual that once in awhile it may be different from your norm.
Even a blood test would not pick up a pregnancy that early... earliest is about 8 days after ovulation and even that will be too early for some women.

The spotting could be implantation... could also be your body getting ready for your period to start, or from recent intercourse, if you had a pelvic exam on Sunday, etc..

See what happens later in the week. If your period doesn't show up by the 17th, try a home test at that time. If you can stand the wait, give it even a bit more time just in case your period is a bit late this cycle.