First, congratulations for reaching out to us and sending us your question.
I must tell you that, no matter how badly you want it, pregnancy symptoms take several weeks until they show up. Mild cramping (which you’re already experiencing), constipation, frequent urination, breast tenderness and other such symptoms occur after the second or third week of pregnancy, but it’s too early for you to have them now. The cramping may be caused by your incoming period.
As for your other questions, I always advise my patients to wait 10 days after their missed period to take a pregnancy test. Your body starts producing hCG (the pregnancy hormone) after implantation, which happens on the sixth day after fertilization. If there’s not enough hCG in your urine at the time when you take the test, you’ll get a false negative result.
If your period doesn’t arrive, wait 10 days to take the test. If it does arrive, take the test once it stops. It’s unlikely that you’re pregnant since you haven’t had sex around the time of your ovulation (which is the most fertile period of the menstrual cycle), but you should still take the test to be sure.