It is great to hear you are visiting Ireland very soon.
All children between the ages of 12 and 17 will be required to have a negative RT-PCR test taken within 72 hours prior to arrival, even with fully vaccinated or recovered adults when they enter Ireland. Unfortunately, one dose of the vaccine is not enough to be considered "fully vaccinated", and authorities will ask for the negative test upon entering Ireland. You can read more about the requirements to enter Ireland in the Traveller's health article
and the Irish Government Website
I hope you find this useful.
Wishing you safe travels,