Okay I Just Got A Positive On 8/17/15 And It

Okay i just got a positive on 8/17/15 and it was at 1 am then at 3:30 i went to the clinic and they did two test and they were negative if estimated i would be around 4 weeks i have my first appointment on the 24th... Im not so sure if i am pregnant anymore.. And this is my 2nd pregnancy my first one was via c section. Ive been gagging for the past 2 days and been having this wierd pain underneath my belly button where my pelvis is on my left side is that normal?... Lower back pain and my period was supposed to start yesterday no sign of bleeding just small cramps. Im hating the smell of peanut butter now but i used to put globs of it on my sandwhich. I dont know if this is all in my head and i dont want to be dissapointed or have my db disappointed as well knowing this is his first. What am i supposed to base this off... And then i eat like im starving then for the past 5 days ive had this nervous feeling in my stomach like your sitting in a crowd of people or on a stage is that normal?.. I need reassurance.. Bc idk what to do the appointment will do blood work and an ultrasound... I just dont want to go in there and find out theres nothing in my uterus or that im not pregnant... Please help