Hi there ~
To answer you question, Chlamydia cannot cause a delayed period. I think you missed period is either because you have become pregnant or due to another reason. It is better to wait it out for another week and get a urine pregnancy
test done. Also consult an obstetrician to find out if there is a cure for chlamydia since it would help with your sexual hygiene.
I hope this helps.
Take care and have a lovely day !