Those who are doctors, nurses, and teachers are considered Islamic professions as they serve humanity. Since all actions should be done for the sake of Allah, how can one perform other professions, like engineering, for the sake of Allah?
The intention of serving people can be with doing any work in any field in the life. Everyone who is doing any service to people can keep such intention so that he will get the reward of serving people. Engineering is also a field of serving people and you can have the intention of serving people while you are working in any engineering field..
'Wassalam.