Hi,
I’ve been in a similar situation like you. My best advice is do the ATPL exams first. You can do the exams with your PPL only. You don’t need to have a EASA medical for the exams but I recommend you get one before starting anything. Since you have 150 hrs, you can get a validation in order to train for CPL/ME/IR. You don’t have to convert unless you want. The only issue is you’ll have to go back and get your medical renewed till you get the EASA CPL/ME/IR.