To determine the length of your pregnancy, you can start by counting from the first day of your last menstrual period (October 26). However, keep in mind that conception usually occurs around two weeks after this date. So if you got a positive pregnancy test on November 28th, it means you are approximately four weeks pregnant. This calculation is based on the assumption that you have a regular 28-day menstrual cycle. If your cycle is longer or irregular, it may affect the accuracy of this estimation. It's always best to consult with a healthcare professional for an accurate assessment and to discuss any concerns or questions you may have about your pregnancy timeline.