Period/Pregnancy

Hello everyone!! I need help trying to figure something out so for the past two months I haven’t gotten my period it didn’t come all of August, in September it was kinda of like spotting but it wasn’t how my normal period was and October just started and it still hasn’t come yesterday I took a pregnancy test to find out if I was pregnant or not and it came back negative which is weird to me because I have been having pregnancy symptoms. Can someone please explain to me what is going on? I’m 18 btw

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