I’m curious about the differences between the expressions '다면서', '다니까', and '다고 해서' in Korean.

I feel confused by expressions like '다면서', '다니까', and '다고 해서' while learning Korean. For example, looking at the following three sentences, they all convey the idea that 'Andy must pass', but the nuances and situations for using each sentence seem different. 1. Andy is studying because he has to pass. 2. Andy is studying hard because he has to pass. 3. Andy is studying hard because he was told he has to pass. I would like to know how these sentences differ and in what situations each expression is more natural to use. As a foreigner studying Korean in Gangnam, understanding these subtle differences is challenging. I would appreciate your experiences or advice!