I finished my period on the 24 sep normal cycle on the 25, 26, 27 we had unprotected sex on the 27th I had been spotting in the morning then it stopped. 4 days later I started to bleed again heavier then usual is this normal?

Its not normal, but its not unusual. I doubt if it's a sign of pregnancy. If you continue to bleed then you need to consult your doctor.