I'm late

I was supposed to get my period on the 5th but didn't. I tested that afternoon, negative. I tested this morning (the 6th), negative. My cycles are irregular but usually I get it by now. One of my apps says Monday the 8th. I'm not cramping like I normally would before a period. My fitbit says my resting heart rate is up 10 beats more than normal and it's been like that for almost a week. If I eat i can't finish because I feel like I will be sick. I'm SO confused. Any suggestions?