First things first, you must not go against your parents. That means you should try to convince them using reason, not emotional drama. Find out what their concerns are and try to communicate to them why you want to join the services, and I am sure after they've seen your passion, they will agree. Tell them that even in civilian life as a regular engineer, you will be subject to your seniors' will and will, likely, need to kiss-butt anyway. At least if you do your time in the Army/Air Force, you will be rewarded. In civilian live, with all the bureaucracy and politics, there is no guarantee you will succeed.
If it comes down to it, tell them to come with you to a recruiting and have them speak to the recruiters directly.
Out of high-school, one option I had was to join the Canadian Forces and complete my education at the Royal Military Academy, serve the mandatory 5 years, and then go to Pak to join PA/PAF. After speaking with my dad, I realized the many problems with this idea, and changed my mind. It took a few months, but gradually I started seeing things from my parents' perspective. I am so glad I did that.
Conversely, a Vietnamese-Canadian friend of mine joined the Canadian Forces against his parents will, and quit in less than a year. He hadn't thought it through and didn't discuss it with his parents. Now, he's too old to go back to high school and too under-skilled to get a have a serious career. In the last 5 years, he's joined the Army, Police Academy, Security Guards, etc. Each time he's quit in under a year.
That is an opinion. Most people believe Electrical Engineering to be the toughest, particularly the Electromagnetics and Systems Control fields. The field of Nuclear Engineering is also very difficult.
In India and Pakistan, Aero is very easy, mostly due to the level of R&D. My fellow-students in Aero dropped out of IIT and came to UofT for its Aero program.
