Although your landing page includes the following statement:
All the collected data is subject to a strict confidentiality and anonymity criterion.
You do not link to the details of those criteria and your survey is not hosted on an official University website. So this will result in you getting many fewer responses, and tending not to get responses from more sophisticated users.
You should discuss this with your thesis advisor and see what the usual university practice is in your program. Many accredited schools, particularly in the EU and the US, have very specific rules about how thesis surveys can be presented, collected, and how the privacy policies are given to participants.
We’ve had a number of university students offer surveys of this type through this forum, and the ones that were hosted by the University with links to their privacy and usage policies typically got a lot more responses.