17 days no period showing....?

Period was supposed to be here 17 days ago.. have had some cramping, have had twitches in my lower stomach at times, when I lay on my stomach feel like there's a ball or something in lower part, nauseous at different times of the day, brushing my teeth and the taste of the toithpaste makes me gag and this has never happened before, breasts been sore but yesterday and today they are very painful and my nipples seem to be red with some bumps around them. I hae taken two tests one at 4 days late and another at 11 days and both were negative. Is there a chance I could still be pregnant but just not enough hormones in my urine? I took both tests in the middle of the days.. any advise would help.. and yes I know none of you are doctors, I'm just asking for advise...