need advice !!

Two weeks ago I saw the gynocologist for experiencing five days of dried blood two weeks before my period should have started. They tested and said everything was fine and most likely just hormonal. They also took a pee test and pregnancy was negative. I am now 4 days late on my period which is not normal at all! My periods are like clock work almost down to the times! I have taken two pregnancy tests, both being negative. Now here is the kicker ( no mean comments I'm hard enough on myself). I have been a smoker and I heard that if you smoke your hcg levels will not show on a pee test. I am also cramping and very concerned that I am pregnant. Is there any other way to find out so I can ensure I'm taking all the safety measures to have a healthy baby. I stopped smoking two days ago in fear that I am pregnant and hurting the baby. I know something isn't right with my body. Ahh someone please tell me I'm not alone !!!