Late period negative pregnancy test

Okay so I have taken 2 pregnancy test since missing my period I am on day 4 of a late period and I know my body pretty well even under a lot of stress I will still start and even if I ovulate late I will still start on cycle day 28 and now I am on cycle day 32 and really confused I’m just wondering if anyone has went through this as well I’ve been really tired and some what nausea and I’ve been having dizzy spells from time to time I’ve also been using the bathroom a lot