Dear emotion driven brother, i think i won't be wrong if i assume that you are inclined towards PSP or CSS after being through the grand massacre of our children and brothers in the most condemnable Peshawar incident.

Dear, you are the most concerned person regarding your future and you should be!

Here are some humble observations i draw from your query:
1. I am unable to understand that you are a civil engineer who wants to become a scientist like Thomas Edison in Pakistan.
2. You were thinking to apply for graduate studies and establish your own industrial research-oriented lab in Pakistan
3. Peshawar incident, your parents, and your Principal (Tahira Qazi Shaheed) want you to opt for CSS.
4. You want to become a scientist whereas, you had fascination to join fighting force too!!! ?? You wanted to become Pakistan's Thomas Edition but never wanted to become a scientist and never liked it. (I am just making my point, not criticizing you)

Now my dear, No ONE can advice you anything better than yourself.

You should first enlighten yourself what do u want to do!, A scientist, a fighter (army men), or a PSP.
If you are opting PSP to make a change and serve Pakistan, pardon me, your view is very narrowed.
If you want to become a scientist, have the potential, i think that is a wider prospective. You may get back to Pakistan after completing your higher studies. (Like our Quaid did)
and serve the nation and instead of become a martyr fighting some corrupt, criminals or taliban (I would say charsis, bhangis, smugglers); become a living legend like Dr. Abdul Qadeer Khan who made us and Pakistan INVINCIBLE !!!