Emanuela Your are correct. A trying moment is a difficult moment, but the adjective trying means more than 'difficult'... it means "extremely annoying, difficult, or the like; straining one's patience and goodwill to the limit: e.g., - a trying day (like a day filled with much stress); - a trying experience (an experience that required you to be very strong or patient).

"Trying" can be thought of as "testing". For example: try my patience -> test my patience Native speakers use both terms. When a moment is trying, it's testing your ability to cope, to find a solution, to find a way forward. You might also see "tried and true". This is similar: a method of doing something has been tested repeatedly (tried by many people at many different times) found to be effective. So the method was tried (tested), if was successful, so it's a true (good) way forward.

Yes! "Trying" also usually means it was emotionally straining, or made you feel anxious or stressed. "Difficult" doesn't have an emotional meaning. A "difficult" job can still be fun, but a "trying" job wouldn't be.

Yes.