As far as not having a medication history, I didn't have one until I was in college. My mother didn't want me on Ritalin or strong medications while I was in middle or high school, even though the school nurse had recommended it.
ADHD medications are powerful and I just told my doctor in college that my mom felt that the medication was too strong and that was why I never took it, despite my middle school and high school nurses recommending it to be given to me.
If you go to Peru and go for a consult for an ADHD evaluation, they will likely ask you about your childhood history, academic background, and other instances in your past where ADHD symptoms occurred. ADHD presents in childhood, so try to remember some examples of times from your childhood that you can share with the doctor you see. It's going to be self-reported, so you will likely be diagnosed with ADHD if you demonstrate a history of symptoms beginning in childhood and that are still having a negative effect on your life. It will be helpful to have examples of times in your childhood where you were distracted or had difficulty with concentration. You can also explain different coping methods that you may have came up with to help yourself with distractions.
There are many different medications for ADHD. Outside of the US, the options are limited. Personally, I had a rough time being prescribed several different medications before I found one that "worked" for me. I tried Concerta, Vyvanese, Provigil, Ritalin, Straterra, and Adderall. Adderall was the one that worked for me (the extended release one, not the instant release one). The other ones had varying degrees of side-effects, with one (I believe it was Straterra, had me disassociating and called 911 because I thought I was dying). Several of these were given to me by my doctor as free samples to test out. You're going to be limited to just a few ADHD meds in Peru, so just be careful with the dosage and be careful for any side effects.
Your body/brain chemistry is unique and the medication that will help you the best is not going to be the same as the one that works for other people. Unfortunately, it may take some trial and error before you find the medicine that best helps you. I'm wishing you luck. I wish I could offer you more help.