High fertility right after period?...

Dee
Hey ladies,
So I'm off my BC pill and a few days after I came on my period then when that ended I started my period again after a week (thus past monday) it's ending now and according to this app it's telling me that the next day after my last period day my chance of pregnacy is 27%....
Could this be true?. I know my body is trying to get back on track it just seems odd to go to that percentage that quickly. 
Thoughts, tips, advice would be nice ☺️☺️☺️