Why Are My Periods Late This Month?

Hello. I have a regular 28day cycle. Never been late for a period. This month my period came 3 days late, this is quite unusual for me. I have been trying to conceive for 5 months now. I have been getting very tired, feeling very sick and my breasts are very sore. I ve currently been bleeding for two days, the bleeding isn t constant, it s kind of on and off. I am just wondering if I am pregnant? I haven t taken a pregnancy test yet, I am awaiting for the bleeding to completely stop.