Am I pregnant or is something wrong with me?

Hi lady’s

So my period is 15 days late and I had spotting (color was brown and light pink) a couple of weeks ago. So my symptoms now are my stomach feeling weird as in tight but bloated and full and back aches my boobs are more firm then normal but are not sore...also idk if this had anything to do with it but my nipples have been getting hard outta no where and it’s not how my nipples normally are ..anyways I have felt tired and have been having headaches! But I took a test about a week or two ago and it said negative...so I have no idea what’s happening. I need opinions or advice!