Could I be pregnant?

My SO and I began TTC last month and have been having sex daily, even (TMI alert!) on period days. It's been about two weeks since AF and for the last two days I have had sore breasts, some cramping, and reoccurring headaches which sometimes make me nauseous. I know it's too early to test and I might just be psyching myself out, but could these be early signs? How early can a woman begin feeling symptoms?