I am gonna be blunt here. You, my friend, are headed for depression if this obsession with CSS and foreign service goes on. Try to control yourself, man.
If this is something you want, Work hard. Pray to Allah to show you opportunities to better yourself and never, ever leave anything to chance or luck.

BUT.. be realistic and don't give yourself any false hopes. Obsession with anything that is not in your control (and nothing ever fully is) will lead you to huge disappointments and mental health problems. Look at the stats and know that every single person who sits in these exams, they too are passionate, hard-working, good people. But not everyone succeeds. Even if you don't make it, know that you tried your best.

The other day I was reading a post where a person asked kinda the same question as you, the question was like 7 years old maybe. All the responses were hilarious. Dismissing any notion or chance of failure and bashing the OP of being a pessimist. Essentially all of the replies were implying that "yeah people fail CSS but we will not if we try really really really hard and if we pray even harder. Nope no chance of failing" One of them even went on to say that "I literally HAVE TO pass this exam or else I will do nothing else. ". SURPRISE, SURPRISE, I went on and checked their post histories. 99% of these deadass dreamers ventured into other government jobs and gave exams. Even the "will do nothing else" bhai sahab gave other Government institution exams and started threads about scholarships and other jobs (i hope he succeeded) and stopped participating in posts related to CSS.

Do not put all your eggs in one basket. Work hard, work your best, but understand the unpredictable nature of the exam and acknowledge facts. Do not resort to confirmation bias and do search up interviews or articles of people who succeeded and did not succeed. Everyone who sits in these exams (even multiple times) takes risks, puts effort, and prays to Allah but Allah knows what is better for us.
Again Work tirelessly towards your goals but also surrender to the will of ALLAH. Whatever it may be.