Just a question?

So I should not expect AF for another 5 days even though we are trying to conceive! I have had lower back pains, mild cramping, and really bad headaches! This morning I woke up out of my sleep with a headache and nausea and vomiting! So I took an hpt and it was negative could it still be to early for my BFP? Ps we did have sex during my ovulation!