Is it possible?!

Is there a chance you can still be pregnant 1 day before your supposedly missed period and up until then only got negative results on all tests?! (Never used a first response...only cheapies) I mean my periods aren’t regular since I lost my last baby in December and only had 1 period since then. I tried tracking ovulation on this app but I’m not 100% sure I got it right nor am I 100% sure about when my next period is because of the loss. Just going off of what this app says basically. I guess I’m just looking for a little hope that there’s still a chance I conceived this month. 😕😢💔