Thanks everyone for the replies.
An update, suprisingly, I passed the class 1 medical examination, without clearing the "blow in the bag" test for the lungs and even more suprisingly not needing to visit a cardiologist. About the lung thingie the DME added a note as well that I'm small built so naturally he doesn't expect me to have a big lung capacity like those giant adults.
And the DME verifed that BMI is not an issue and I'm a living example.
Cheers!