wondering if pregnant..

Me and my boyfriend usually have protected sex. But on the 21st we didn't and he did not pull out all the way before he came. I am supposed to start tomorrow but usually when I am about to start I cramp for two-three days before hand but I haven't. And if we have sex around the time I'm suppose to start it usually speeds up the cramping and I start soon but that also hasn't happened yet. I'm starting to gt anxious and worry. Any advice? I've decided that if I do not start by the 4th I will take a test.