Started birth control early and missing period

I have always had bad periods and finally at 18 have gotten on the pill. My doctor told me to do a Sunday start and I thought that my period was going to come sometime around this weekend (Fri-Mon) and went ahead and took the first pill to have a Sunday start. Now my period has still not come (on Tuesday) and I’m kind of freaking out. I’ve also been under a lot of stress from my family so it might be that, but has this happened to anyone else before?😬😬