Having pregnancy symptoms but tested negative HPT

I am 18 and a half years old. I had unprotected sex with my boyfriend on the 27th of September, and again on the 9th of October. I had taken a test on the ninth (about four hours before i had sex the second time), but it was negative.. I am very confused as to if i'm pregnant, because exactly THREE DAYS after i had intercourse the first time, i started feeling .. strange. i can't really explain the feeling.. but lately my symptoms have gotten much worse. i have been vomiting, and my nausea comes and goes in drastic waves... my appetite changes drastically (randomly). For example, i ate three plates of spaghetti in one sitting, and then the next time i ate (i wasn't hungry till the next day), i only could eat a half of my sandwich... i don't know if this has anything to do with it, but i have also been feeling very stuffy with a runny nose, and have had a nose bleed twice... anywhoo, currently, my breasts feel very heavy and uncomfortable,and are sweating up a storm... i tried putting an icepack on them, but i couldn't even feel the cold on either of them. Physically touching them, they were freezing. otherwise, they feel super warm... oh yes, and i've been having TERRIBLE cramps, been spacing out and forgetting things.. and my acne is terrible...... and mood swings out the wazoo. haha. but seriously, i need some opinions.. has anyone else experienced these symptoms and turned out to be pregnant?? Please help.