four to six weeks ago. If you know when you had your last period, then you can go online to many sites, such as americanbaby.com to see when you would have been ovulating last month. Also, pregnancy tests are only around ten dollars, you could test with first morning urine
, if you are late for your period. First response and other "early response" tests can tell up to four days before you are due for your period. If you do get a positive test, then you would have to see your doctor of course. Good luck, I hope you get the answer your looking for very soon.