Could I be pregnant

So The weekend of July 15th-17th my boyfriend & I had unprotected sex wild,wild doggy style sex. However at one moment I felt a warm sensation like liquid inside, and pulsating as well. He didn't moan as a man would after he ejaculates he just slowed down then kept going after I felt that warm sensation. Now for the past three weeks I've been nauseous, slight cramps & headaches. Eating peanut butter with crackers like crazy to which I never ate peanut butter like that ever before, past two days I've been suffering with heartburn. Could I be pregnant? Aunt flow isn't due for another two days is it to early for me to test now? PLEASE MUCH NEEDED ADVICE‼️