Implantation bleeding or af?

Hi girls! I have been ttc for 9 months and i was 2 days late for my af and it finally came but was light and only lasted 3 days which is very weird for me because it was more spotting. my periods are always on time and lasts for over a week and are always heavy. But once it stopped randomly I haven't had anymore bleeding but still cramping but only on one side. Anyone else had/have the same problem?