HELP!!!!!!!!!!!!!!!!!!

My period is 17 days late! It's never been this late before. I don't know what to do. Please help!
Update : I have taken 3 pregnancy tests... one from the dollar store and it came out negative and the other two were rite aid brand one said negative and the other one I think wasn't used correctly because it got wet where the results come up and that one would read positive. 
The order of the tests that I took were : positive, negative, negative
Update 2: this morning I went to the bathroom and I'm experiencing spotting, what does this mean???

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