Confused

Kerry
I am newly off birth control (this is my third month) and have had very regular periods all my life on BC and the first 2 months. Now I am nearly 2 weeks late and have negative pregnancy test. I have off and on tender nipples, constipated, and cramps. 
Should I go get a blood test? Where do you get blood tests done?
If I'm not pregnant how do I know when I'm going to ovulate next or when I should take another test next month? Is it possible that I will not show on a home test? Any help would be wonderful! Really wishing we are pregnant but having fun practicing for the time being ;)