It's 16 days since i had sex....test showed up negative. Could i still be pregnant?

I've had sore throat since i had sex. I've got a bit of a cold as well. I've gained a lot of weight around my tummy everything seems tight. I can't stop eating I feel hungary. Ir's 28 days today and my period hasn't started my boobs are all sore and my bra feels tight. I had a few headaches as well. Am i imagining or could i be pregnant? He penetrated me without a condom and than put a condom later.