Late period? But period symptoms? Pregnancy?

So, for the morning of July I had protected sex (and the condom did not break), moving forward to now, my period has been late 4 days. On the third day of my period being late (keep in mind I had , had sir nipples which is my major indicator that my period is coming) I took a pregnancy (first response 6 days sooner) and both of the tests (I took 2) were negative.

I still have not gotten my period. But I did notice that my cycle days were getting longer as they went from 26-28 days to 30-32 days. I’m still a teenager so is it possible that my cycle is just changing or should I take another pregnancy test?