First time pregnancy help? (GIRLS ONLY..)?

Ok, I'm 16 years old and I live with my boyfriend (who is also 16), his mum, dad and 4 younger siblings (I moved here by choice and my parents let me) ANYWAYS, I think I may be preggos. For people who know me would say I am a very mature and bright girl. So, I took a pg test today and showed up negative but I am not convinced. I feel very different. My boobs seem a tad bigger, and are sometimes falling out of my bra.. last week I had a very hungry appetite, if I ate a whole dinner plate, I'd still be hungry, and right now if I eat, I feel VERY sick. As if I can't keep my food down.. I also had the two BIGGEST cramps a few days ago, most painful I've had and lastly .. no periods. I can't remember exactly when but my last LMP was at least a week or two before my 16th birthday and I turned 16 on the 10th of May. I'm not a stupid girl, I know how to take care of a baby and I know for a fact I'd be good at it. (theres a baby here who I treat as my own and I also tend to her at times) But my real question here is, if i am, do I keep it? I mean i would love to keep it, but i don't want to disappoint anybody. could i get some experience storys from you guys? im really stuck, i think about it all day every day. the room we live in would not be big enough for a cot, BUT can be moved around to make it fit. i have 2 other tests left cos i baught 3, trying again tomorrow morning.. PLEASE HELP, i need help making my decision but bare in mind, I'll feel really bad if i terminate it... and ill be upset and cry