en çok üzüldüğüm noktaysa ilk sınavımda dikkatsizliğim nedeniyle düşük almış olmamdı.Bundan sonra dikkatimi ne olursa olsun diğer zamanlarda olduğu gibi sınavıma odaklayacağım.
The most upsetting was getting a bad mark on my first exam because of my carelessness. From now on, no matter what, I will focus my attention on my exams like it used to be.
Before edits:
"The saddest point was get a bad mark because of my carelessness in my first exam. From now on, no matter what, I will focus my attention on my exam like the way that it used to be before."