How early??

I have different fertility apps. They all say I start period/ovulate on different days. Two said I ovulated in the 17th. One said on the 14th.

One of my apps said my period will start in 4 days. So I took 2 tests just to see. And they were both positive.

With my last pregnancy, I did the same thing but the line was very faint. This one came up fast and dark. I’m confused. I thought when you are early, it would be a really faint line. Wondering why it came up quick and dark?

Also, I’m 35 and this will be my fourth pregnancy/child.