implantation bleeding or period?!

Hello ???? I have been trying to conceive for a year now the past two months I have been taking seven seas trying for a baby. My cycle was 28 days and this month my period was due on the 25th but never came till the 30th. I have felt dizzy, tired and cramps. On the 30th me and my boyfriend argued and i was upset, i came on straight after the row Im not sure if that caused it? Later on that day i had a bath and had to jump out and lie down because i felt like i was going to pass out. My period started of heavy which is normal then two days later its a light pink and minimum which is unusual. Please any advice? Could I be pregnant? Thanks