Is it Possible?

My period is due April 15 (i know it's still early), and i ovulated April 1. My fiancé & i had unprotected sex on Mar 26 & 28. No pull out & no protection either time. Over the last week i've been extremely exhausted - taking 2 hr naps every day when i get home from work and still sleeping like a baby at night. I've been nauseous enough to where i can't eat any of my favorite foods, more of the greasy foods though. I've had hot flushes almost every night. And over the last few days my boobs are incredibly sore on the outsides. They also feel extremely heavy and full. I tested this morning and got a negative result.  Is it even possible that i could be pregnant?!