PCOS, pregnancy symptoms, and negative HPTs (all 5 of them...)

This is possibly the craziest thing to consider for me, but it's all I've been able to think about for weeks. Ever since just after Christmas, I've felt, well, pregnant. If I were I'd be almost 8 weeks along, I'm assuming (my boyfriend and I rarely have sex, let alone without a condom, so I can only count back from the day I got birth control and had a brief moment of spotting). 

Basically, I've thrown up four mornings since Dec 26, always within the same time frame, I'm constantly queasy, constipated, gassy, irritable, and sore. I have horrible insomnia at night and never feel like I'm getting enough sleep. For about two weeks straight I could smell the entire fruit and veg section at Walmart as soon as I walked in the door, followed by the boxed cake mix aisle, the fish section, and the spices section, and now I don't have much sensitivity to anything except cigarettes (and as a smoker myself who can't smoke this is killing me).

Around the time I had the enhanced sense of smell, my pee smelled sweet all the time, and my roommate told me that I "smelled pregnant", whatever that means. 

Now, I'm breaking out everywhere....on my face, chest, arms, and legs, even. I'm constantly itchy, dizzy, feel on the verge of my migraines. My breasts seem to be swelling and feel like water balloons, and one of them is even bigger than the other now. As well, I actually noticed tenderness today when I took off my bra. My cervix is soft and squishy (for the first time ever) and it's actually uncomfortable to stretch when I'm on my stomach, which is odd considering I'm a rather large person (290lbs, size 22) who can practically float on my belly. 

I don't know what to think; I know that for a person with PCOS, who wasn't on birth control, or metformin, who rarely has sex, to get pregnant without assistance is insanely unlikely. I have taken 5 HPTs, all but one in the morning, all negative. I don't know why I can't believe them? I feel like maybe I've read so many symptoms that I've convinced my body, or something. Help?