PLEASE HELP ME , Not a missed period yet but having nausea, worried about pre cum and pregnancy 😭

So I had unprotected sex three days ago now three times in a row and I've been really worried about pre cum. I had sex three days before my ovulation date , and tomorrow I will be coming on it but sperm can live up to five days. So this could of increased my chances. Obviously it's way to soon to see if I've missed a period. But yesterday I didn't have like sore sore breasts they just felt different that usual. This also isn't my period as I don't expect it for another two weeks and it's regular. I've just woken up now this morning, and felt really really sick but not going to be sick(yet) it's all acidy and I feel really gassy too. Is this normal? Could I be pregnant and has anyone else thought they were pregnant even before their missed periodÂ