For starters, count to 28 days from the first day of your last period. This won't be exact, since every woman is different, but it will give you a ballpark number for how late you are, and then you can follow the directions of the pregnancy test for when it is effective (how many days after the period is missed, or after conception). If it comes back negative, take another test a few days later.

I do believe I got pregnant my first time with no penetration. I am very fertile (pregnant at the drop of a hat), as was my mom and my sisters.

I couldn't take birth control pills when I was in my twenties, as I was too sensitive to the hormones, but today's pills are much less strong, and I can tolerate them fine. So maybe you can find pills that don't affect your migraines. My daughter has taken birth control pills for over a year and is not yet sexually active. (Probably everyone will laugh and think I am just deluded, but I really do believe her. We are very close and talk openly about many topics including sex.) She went to the doctor to get the prescription "just to be ready." (For most of my sexually active life, I have used a diaphragm, so that is an option. Also, IUDs.)