At 18, you don't need your parents permission to get tested. You're an adult. Of course, being in a place where you don't speak the language is an issue, but when you get home, you can go test.
In the meantime, a slight burning can be signs of many things, including dehydration. How's your water intake? Make sure you are drinking plenty of water, decrease caffeine and alcohol, and see if that helps.
Urine can also be impacted by spicy foods, citrus, tomato, onion, etc. Water can help with that, too.