Welcome to HCM.
There are always chances of pregnancy
because you had intercourse during fertile period.Mild spotting may occur during cycle date even if pregnancy is there.
You have to go for urine pregnancy test after 7th day of missing cycle ideally.
Otherwise you can also confirm it by blood hcg
level and USG.
If you are pregnant and you don't want pregnancy than consult your gynecologist for further management.
If you don't want pregnancy than you can start oral pills
which will be also helpful to regularized your cycle.