"You're in the Netherlands, speak Dutch."

I hate the people at school sometimes- especially the teachers. I am a Dutch citizen, I was also raised in England. Most of my childhood was spent in England and I have been exposed to English for about 80% of my life (my parents speak English to us). I'm not sure if it's common knowledge but Dutch is one of the hardest languages to learn because of all of the exceptions in grammar, I have trouble speaking it even after 7 years here.

When I'm with my friend i often speak a mix of Dutch and English, if i get to a word i don't know the translation of i just switch to English. This is for comfort and occasionally we get questions about it, but there are always some people who tell me "Je bent in Nederland, spreek Nederlands." (caption). I hate this. It makes me angry and insecure. I'm trying to speak Dutch but half of the time if i get something wrong I'm either told condescendingly I said it incorrectly or they just laugh in my face.

My friend has never laughed at me, sometimes with me but then it's always lighthearted. If I switch the language she speaks English with me (I have to admit since i met her she's become really good with it and I'd consider her fluent) I was talking with her in English and suddenly the teacher called "SPEAK DUTCH" from across the room, (this is a new teacher, if teachers tell me to stop speaking English i usually just listen.) it was so embarrassing, half the class turned to me. Why do teachers do this? Why can't they just be calm- or perhaps just let me feel comfortable speaking instead of pausing for thirty seconds because I'm trying to think of how the hell you say "zodiac sign" in Dutch??