Hi klc,
as long as you have unprotected sex, there is always a chance you could fall pregnant. Women usually ovulate 14 days before their next period is due, keeping in mind that everyone is different and it is possible to ovulate at different times. As for symptoms in early pregnancy, once again everyone is different, some women don't have any symptoms up until 3 months into their pregnancy. If you were to experience early symptoms, the most common ones to watch out for are tiredness, nausea, sore or tender breasts, sensitive nipples and frequent urination. It is possible to get an accurate result on a home pregnancy test once your next period is due, some tests will state on the box that it is sensitive enough to detect hcg levels a few days before your period is due. Alternatively you could go to your doctor and request a blood test for a more accurate result. Have you considered birth control or some other form of contraception ? I'm sure your doctor would be happy to discuss some different forms of birth control that would suit your needs.
Good luck...
Suzy