taking a pregnancy test

I have other apps that I use as well.. with different dates telling me when I should start me next period. I took 3 pregnancy tests.. 1 digital which came back with a question mark the other two say negative, now back track to the apps I currently use.. one says perios is in four days.. next app says 5 days then this one says 8 days as another app says 8 days.. I have some months where my period comes 36 days.. but at most 26 to 28 days approx.

my last period started may 7 of 2018.

so my question is when should I take one.. seeing as I took 3 already and was a tad disappointed.

I already have a 10 year old and I'm now 30