Circumstances would contribute to your situation. What are the most stressful circumstances contributing to your current situation? He comes from modest circumstances. (Financial) The situation is unbearable. The circumstances are unbearable. (Similar)

@Liam, thanks for your help.

As you said they are quite similar but you can think of circumstances making up a situation. So a circumstance can be a single condition or reason but a situation is the whole environment. Does that make sense?