help!! confused!!

So i got my period on the 12th as usual an it was a normal 6 day period. I babydanced on the 18th an I just now hit my fertile window but today I woke up with extremely sore breasts an have been so tired all day long. Felt a little nauseous this morning but that was it. So my question is can anyone give me their opinion on what the heck is going on with me ? Has this ever happened to anyone else and is it possible to get pregnant a day or two after AF ? Could I have ovulated earlier than expected?