experience traveling with prescriptions?

I'm flying to Peru in a few weeks. I have an adderall prescription (stimulant, controlled substance). I've done my online research, am getting a letter from my prescriber, and know it needs to stay in its original container, etc.

I'm just wondering if anyone has personal experience visiting a different country (preferably Peru) with a prescribed controlled substance. Did they ask you any questions about it? How much of an issue was it? Again, I've been doing online research to be as prepared as possible, but hearing other people’s personal experiences is very helpful for me and my travel anxiety.

Thanks in advance!