Linea nigra

I thought this line only came out on pregnant girls and also heard that some girls have them since they are small but I pretty sure like 85% sure that I didn't have this line or at least not this dark cause I just noticed it I am extremely bloated.... on may I missed my period on may then on June I had a weird period and now I been feeling flutters and twitches in lowers stomach frequent urination and now this line just shows up should I test even though I still need 3 weeks for af to arrive? I was got a faint positive back in May when I missed my period but I checked the test 30mins late so I didn't think much of it thought it was an evap line and didn't retest after that

So what do y'all think or does anyone know why this line shows up if not pregnant related?