My period is irregular so i dont have a set date i get my period it comes between 28-39 cycle days but the average is the 33rd cycle day. My app says im

Due for my period sept 11 which is cycle l day 35 l, i would say i ovulated in 20th cycle day which was august 26. I tested on sept 6 and 8th which was cycle day 30 &33 both were negative. But ive been feeling slightly nauseous and my nipples are bigger .

The day i ovulated and had sex

The two days i tested