Could I be pregnant?

Jessie
Hi 
I want to start by saying that I've never really had a regular cycle until after I had a miscarriage in May of 2015 I found out at 5 weeks then Went back for 8 week check up and baby had no heartbeat since then I've started eating healthy and lost quite a bit of weight trying to get my body healthy to try to conceive again. My periods were back on track for about 6 months and now I'm three days late! I've also been keeping track of my peak fertility on this app and had sex three out of the four days of my peak and have also had sex after my peak time  I took a home pregnancy test Wednesday and it was negative did I test to soon? I usually start between the 25-29 of every month. How long should I wait to test again? Or make an appointment to see a dr?