My period is 12 days late. It is usually right on time every 28 days. I have been feeling cramps off and on, have taken 2 pregnancy tests and they have both come back negative. I have heard I could still be pregnant and should just wait a little longer. I plan on going to my doctor at the end of this week if my period does not arrive. I am not on any birth control and my husband and I had unprotected sex at least once. At this point I have not had a period in the whole month of March. What is going on? I heard cramping can be a sign of implantation but I don't know.

It is possible, but you need to remember there could be other reasons for a delayed period beside pregnancy. All you can do is see your doctor and get blood work done and hopefully you will get the answers you need.