late period because of bc ?

According to <a href="https://play.google.com/store/apps/details?id=com.glow.android.eve">eve</a> my period is 3 days late & I've been on birth control but stopped after I finished my July pack. Is it possible my cycle is just thrown off and is going to start late bc of me stopping the pill & not because I'm pregnant. I'm supposed to go get the depo shot next week but if I haven't started my period I can't so I'm going to have to cancel my appt. I don't feel or think I'm pregnant. Advice ?