I can relate completely. Everyone I know thinks I'm super calm and emotionally stable because things that would upset an average person are nothing to me in comparison to what I've been through in the past, and like you, I've learned to hide my emotions when I'm not doing well. It is a really effective coping strategy. I feel like it makes us more empathetic as well because we know what it feels like to be struggling. That's the main reason I'm going into a "helping" career and why I'm a caregiver now.