Am I Really Pregnant After 3 Years?

Hello,

I skipped my period for the month of February. My fiance and I have casual sex, whenever. It use to be every day but now it's less than that because of work and privacy. We have been together for 3 years, we have never used protection because I have a travelling ovarian cyst which the doctors said would go away but I still felt the abdominal pain here and there (in October of last year I found out I had the cyst). We thought I wasn't able to get pregnant since nothing has happened in 3 years, and I had an appointment with my doctor to talk about what I could do now, to help us in the future when we do want to conceive. I am 17, here are the symptoms I've been having: breasts grew a cup size, I've gained over 16lbs since New Years, for almost a week now I have no appetite (contrary to what it should be but I've read about aversion to foods), been feeling nauseas all day and not just in the morning, having the "butterflies" feeling in the stomach, been constipated but feel like I have to go to the washroom, been shaky, been getting cold randomly (contrary to the hot feeling). I would not know how far along I am, I could be a month, I could be a couple weeks.. I have always had an irregular period so I thought when I skipped it was nothing. But I couldn't wait until my appointment to find out so we bought 2 ClearBlue pg tests, they were both positive. I took one in the evening, and one the next morning just this week. Another symptom I forgot to mention is at the beginning of this week I was almost passing out, sweating a lot outside then getting really cold indoors.
Why is it that I am getting symptoms that I have never heard of before? They never teach you this, you never here about almost passing out and yes, morning sickness, but not sickness all day.
I am a little worried. I am very anxious to see my doctor on the 28th. Should I go to a clinic before then to make sure? I heard ClearBlue was just about the most accurate at-home pg test out there and that it usually never lies. Plus, it's a month after my period so I can do it any time of day.. I am afraid that my loss of appetite can be harmful to this possible baby, because I feel no need whatsoever to eat. I have to literally force myself to eat until I can't breathe, or a little breathless if you will (that's when I know I'm full, I've gotten to know my body in different ways since I have no hunger or fullness feeling in my stomach). Should I go see a doctor about this asap?? The boyfriend says yes, he says go to a clinic. But what would a clinic do for me really?

If you could give any advice, ie. what you think, what I can do for these symptoms, how to tell parents. My parents are divorced fyi. I know we weren't being safe and I don't need to hear that from other people, it was our obliviousness that did this. We thought it wouldn't happen to us because medically, it hadn't happened for us in 3 years. We didn't want it to happen now but we also weren't cautious. I didn't want to take birth control because I didn't want my period regulated.

So any help, advice, comments are welcome. Thanks I will keep you peers posted!