I'm unsure

I need your help... My af was due Monday and I haven't gotten it. Took a pregnancy test yesterday and came out positive after 10 mins or so but was very thin. Took a digital clear blue and came out negative. My question is why can that be if it states can tell you 5 days before you miss your period? Boyfriend tells me I have a belly and my nips hurt and right now I'm kinda cramping but nothing new other then craving pickles with pizza haha 😂