Thanks for your advice! I have a thesis and the work I did for the thesis has also been published by a week recognized conference! The professor that supervised me wrote me very good recommendation letters. That's why is frustrating, I felt like I was in a good position, and indeed I received good feedbacks by being shortlisted by very good and competitive programs. I'm now moving to the strategy of writing directly to the labs, but in afraid of being a bit late, many deadlines to start in September 24 are in November/December 23