Thanks for the query.
Usually taking the pills at the same time every day can give complete protection.
But as you took the missed pill within 24 hours, protection can be expected.
Delay in intake of pill can lead to break through bleeding.
That may be responsible for your spotting.
Possibly this will subside soon.
You wait till your expected date of withdrawal bleeding and if you miss the date, go for pregnancy
If the test comes negative, you can continue with the pills.
You can go for low dose pills like overall length or ortho try cylen low etc. Low dose pills may not cause the side effects you are having.