could I be pregnant or is it too early to know?

Today, I have noticed my breasts were exceptionally tender and I've been a little nauseas. I've been feeling crampy for the past few days, with lower back pain earlier this morning. I'm on cycle day 19 and eve says I can expect my next period in about 12 days. During my "fertile week", we had sex at least every other day. What do you ladies think? Have any of you experienced symptoms this early?