So much nausea

Tl;dr: are nausea and cramps at 12dpo common??

Today is my 12 dpo and all my pregnancy tests have come back positive, but I'm still not sure if it's real (blood test taken today, I should know by tomorrow).

Once my gyno talked to me about possible chemical pregnancies, I just chalked it up to that.

I wanted to ask those of you who already know they're pregnant: how soon did you start feeling nauseous? I've been like this all day, and still haven't really eaten anything besides a handful of salt & water crackers. Anything makes me gag, even laundry detergent. My neighbors are grilling outdoors and I went back inside the house because I couldn't handle the smell. I've also been getting some pretty bad cramps, it does feel like the ones I get right before my period is about to come. I feel like there's a constant knot in my stomach and sorry for the following TMI, but I also had diarrhea all day today..

I guess my final question is: how soon did you start feeling pregnancy symptoms?