ANSWER:
What you’re doing is correct.
You should say bismillah when starting a new surah.
I would like to ask if it is proper to Say Bismillah when I am reading Quran that start in the middle part or when I’m reciting Ayatul Kursi? Or the 2 last surah of Al-Bakarah? I normally start from Audhobillahi Mina Saitani Rajeem whenever reading Ayatul Kursi or reading in the middle part.