When was the first day of your last period? Are you currently late with your current period? I was actually trying to conceive and didn't get a positive pregnancy test until I was 2 weeks late... leading up to my period I was getting cramps as though my period was about to start but it never came, and I have still been slightly crampy even after my positive result.
If you are a week or two late definately do a test and see a doctor. A lot of tests you can even get results up to 5 days before your period is due.. which obviously wasn't the case with me, but still..
If your thinking you have got pregnant, search MTP kit it is the solution for you.