Hello, yes it is true that chances of getting pregnant are more if you have sex on ovulation days butit is not 100% as there are other factors playing role in becoming pregnant like your hormone levels, the inner lining thickness of the uterus
and also a few of your husbands factors like the sperm count
, the liquefaction time of the semen etc, so it is not only the ovulation which matters. If every thing is normal don't worry be stress
free you will conceive soon, All the best. Take care.