Hello guys I currently missed my period I'm 12 days late my cycle is 28-30 days I started my period…

Hello guys I currently missed my period I'm 12 days late my cycle is 28-30 days I started my period on February 28th and ended march 4th. Me and my boyfriend currently had unprotected sex from march 6th up til march 16th I've took 3 pregnancy test that came up negative and one that came up positive I also had bad cramps and really bad headache lately and feel like I haven't went to bed for days I'm so tired and I can't stop ratting or peeing a lot I'm so confused someone help a girl out please ( and all my test were done with dollar store pregnancy test )