Short background of me:
I was originally from the Philippines and have learned English for 14 years in school. I came from a family with humble beginnings and grew up surrounded by people who speak either Ilocano and/or Tagalog (Filipino). Although English is an integral part of daily life in my country, where TV, radio, internet and public announcements are mostly in English or a combination of English and a local language, I have not had the change to use proper English outside of school, apart from Taglish (mixing Tagalog and English within a sentence) which is very common for younger people in the Philippines.
I have only really started using English on a daily basis when I started working 8 years ago. I work in technology, whose main language is English. In the Philippines, barely anything is translated from English to a local language. I could say I have a decent level of business English and have never struggled expressing myself during meetings and when writing emails. I have even conducted in-person and online trainings before. For almost a decade, I have worked with people all over the world from countries like the US, UK, Germany, India and France. Of course, my business English skills are far from perfect, but I am really comfortable using it in formal contexts.
Last year, I moved to Malaysia where I got to work with local Malaysians and Indian expats. That was my first time actually interacting with people in English in non-business contexts and on a daily basis. At first, I was really uncomfortable with the way Malaysians and Indians speak everyday English; in a manner which is usually called "Carabao English" in my country.
I eventually got used to it though, until I had to move to Europe for a new job when I realized how "unconventional" Malaysian and Indian (spoken) English were. I currently live with Europeans, all of whom are non-native English-speakers but are very fluent with the spoken language. Interacting with them on a daily basis really pushed my language skills to the limits: I started using properly-constructed compound sentences and the right adjectives and adverbs, and have stopped using non-English words as substitutes when I struggle with their English counterparts. I started stuttering, speaking really slowly, and often find myself using the wrong or inconsistent tenses.
I understand people usually start using English in daily contexts then struggle using it in more formal contexts. How do people deal with this struggle but in the opposite direction? How long will it take before I get comfortable using English in non-formal contexts?