Urine tests negative

Ok this Gonna be long just a warning. Ok so my period is usually very regular and I Now 6 days late I usually have extremely bad cramping 2 days or a day before I get my period and extreme cramping as it comes... I have had none of this. I have been extremely moody and crying over tiny things :( been very angry to loving to angry again had slight cramping but for 30 sec intervals and like 2 times a day? Me and my parter are tryi g for our first baby and are excites about it we just wanna know I have waited untill my period was due then a couple of days later and yesterday ( 13th of may 2012 ) to see and still negative. I have had slight headaches for mins at a time and minor lower back pain boobs have swollen or so my partner has said and have a hard or bloated lower belly I have had gas and exessive trips to the toilet and for more poop then Urianting please help I just want answers? Anything is helpful thank in advance.