Hello, and I hope I can help you today. Pregnancy symptoms vary widely between women, and it really is not possible to determine if you are pregnant solely based on symptoms, because many of the symptoms also occur when women have a delayed period to other hormonal irregularities. All the classically described symptoms of nausea, breast tenderness or swelling (with visible enlargement of the breasts, meaning that your bra actually gets tighter) moodiness, food cravings, and headaches can also be caused by other hormonal problems. The best way to find out if you are pregnant is to perform a home urine pregnancy test. A pregnancy test will be positive within three weeks of conception. Condoms are extremely effective in preventing pregnancy when they do not come off and are used for the entire time during genital contact, so it is more likely that your missing your menstrual cycle can because by other reasons. Stress, weight loss or gain, changes in life schedule or travel, and other medical problems are all possibilities of what can cause your period to be delayed. So if you find out that you are not pregnant, and you do not menstruate for total of three months, you really should see a local doctor for evaluation as you may need some hormone tests to determine what is wrong, and a gynecologist can prescribe medication to help your menstrual cycle to resume. I hope that I was able to adequately answer your question today, and that this information was helpful to you. Best wishes, Dr. Brown