What Causes Bleeding After Intercourse?

I am 21 and have been having pregnancy symptoms and have had bleeding after intercourse that has gotten progressively worse. It has happened three times, the first time it was just a spot, the second time it was a pinkish discharge, and the last time I bled like I was starting my period. A day or so before I had the pinkish discharge I saw a white clot-like piece in the toilet with a very tiny spot of blood on it and there was also a very tiny spot of blood in my underwear. I have not missed my period yet; it is supposed to come tomorrow. I was wondering if bleeding after intercourse that gets worse is normal during pregnancy or if maybe I had an early miscarriage?