Confusion... ?

Sooo, I'm 18 and possibly pregnant my boyfriend left me about a month ago after I told him about the possible baby. we had sex a lot and no protection from either of us I'm allergic to all forms of birth control I've seriously had every single one and my body just doesn't like them anyways I went to the doctor about a week ago and took a test it said negative but the one I took at home said positive... It was odd so I've been going about it like I'm not but I'm slowly gaining weight I lost and I'm eating everything not to meantion for a few weeks I had what looked like morning sickness for a few week. I've been pregnant before but I miscarried at 15 weeks... So I'm beyond scared... I don't know what to do or think.... My doctors are convinced I'm not pregnant but I'm just not sure... ?