As an owner of ATPL, even if you have received a license before 2012, I have to say that you have missed the very easy convert process as of today.

How can a national pilot license be converted into a Part-FCL license?

Existing national pilots licenses will be converted in accordance with Article 4 of Commission Regulation (EU) No 1178/2011 on Aircrew and its amending Commission Regulation (EU) No 290/2012.

JAR-compliant licenses issued or recognized by the Member State before the applicability of Commission Regulation (EU) No 1178/2011 on Aircrew shall be deemed to have been issued in accordance with this Regulation, and shall be replaced with a Part-FCL license by 8 April 2018 at the latest.

Non-JAR-compliant licences, including any associated ratings, certificates, authorisations and/or qualifications issued or recognised by the Member State before applicability of Commission Regulation (EU) No 1178/2011 on Aircrew shall be converted into Part-FCL licences by the Member State that issued the licence in accordance with the provisions of Annex II to that Regulation or the requirements laid down in a conversion report.

As stated in Commission Regulation (EU) No 1178/2011 on Aircrew, the application date was 8 April 2012, though flexibility was introduced via transition measures contained in Article 12 of Regulation (EU) No 1178/2011 on Aircrew and Article 1 paragraph (6) of Regulation (EU) No 290/2012."