Help! Please

I had my first period beginning on February after having my baby back in August. A few days after the app said I should of ovulated I had some spotting. Wondering if that could have been implantation bleeding, seeing as I’m now 2 days past when the app said I should of started.

• I do breastfeed not sure if that could cause period to be late

• I took a pregnancy test yesterday morning and it was negative. 

I know this post is extremely confusing, sorry!