I have two serious questions ladies!

Brittany • Baby boy was born April 21, 2015 at 21:49 weighing 6 lb 10 oz and 19 inches long!(:
First one: AF was due to start today but took a hpt yesterday and got BFP as well as today. I entered in my info and according to this app I'm 5 weeks and 1 day along but how does that make sense if I ovulated on August 27? I feel like this isn't correct. My last period was August 1-5.
​Second one: I've been cramping the 4-5 days like I'm getting ready to start, should I be concerned? I'm very worried because my husband and I miscarried just last month.
​Any answers help, thank you all in advance.