I've been on the pill for a while now (always on time, never skip or forget to take one), and I am paranoid about pregnancy.

My period finished last sunday, and I started taking my pill again monday. I was sexually active on monday night after taking my pill, and once again on tuesday. Today (friday) I've been experiencing cramps in my stomach very much like a period cramp, but very randomly and both upper and lower abdominal regions. It's not brought on by anything, and I haven't exercised that area in a week. I did have some mild strain-pain on monday from doing crunches, but this went away quickly.

I'm only on the pill as my partner and I have decided not to use condoms any more, but even though we are both comfortable with the idea of becoming a family, I'm scared I'm pregnant. I was going to do a test, but I don't think they can pick it up this early.

Help?