ovulation moved?

Alexis
So I was supposed to ovalute on the 3rd and period was due 18th but as it hasn't come, glow has moved my ovulation date to the 5th. 
I tested on the 16th and it was a bfn, does that mean I'm 100 percent out, as I thought it's too late to test bfp now but as glow moved ovulation I'm not sure. 
Anyone had any experiences of this? (I don't use ovulation tests so no idea when I did ovulate) 
Thanks in advance 🙂