A minimum of 6 hours of sleep is sufficient like a software engineer like you. The quality of sleep is important rather than the duration of sleep. If you are able to sleep well for 6 hours, there is no need to worry.
Maintain an erect posture at your work desk. You need to move around from your seat every 2 hours for 5 to 10 minutes. You can use a small back cushion if you experience more pain.
There are no additional tests that you require for the back pain
Indulge in some amount of physical activity every day so that you get sound and quality sleep.
You should be able to take care of your own body according to its needs.
Hope this helps.