Most of my friends are bilingual or even; able to speak more than two languages. My dad is bilingual, although my mom is not. My siblings are bilingual.I took a test recently and was determined as "native fluency" for English. Apparently I watched too much American series, somehow it helps. Amongst my friends we had this joke circulating; how do you know when you actually speak more than a language? When your shopping list starts to look like this;
Gula
Cooking oil
Chicken stock cube
Sayur sawi
Eggs
Tempeh
Susu
Apples
Beras
When you interchangeably use both languages daily without moment of hesitation. Writing down a list, these words just pops up in your head without a second thought. It's even funnier to read a list made by a friend who's trilingual. She even writes Chinese characters for some items as she said it's shorter in Mandarin. Her poor English husband occasionally has to text her "hun, what is item no 4?" Before she realises that she has been writing it in Mandarin. When I speak, I did so without a break when I use both languages.
A typical introduction to another bilingual person (of the same languages) will be something like:Hi, I am Alia. I new staff dekat department ni. If you need any help, I duduk dekat Meja belakang XXX. The HOD mentioned you might need me tolong you in ABC matter.(Roughly translated: Hi, I'm Alia. I'm the new staff for this department. If you need any help, I sit right behind XXX. The HOD mentioned you might need me to help you in ABC matter).
I didn't even once hesitate to include words from both languages in a sentence. Rightly so it should not be that way as it ruins the grammar but I believe every bilingual person who uses both languages in daily exchanging would agree with this to some extent. In my personal opinion, it differs being bilingual/trilingual or first language with XY as second language. Some would claim they're bilingual but to me, the definition of a bilingual is that you understand the grammar construction of both languages and includes them in your daily exchanges. It's not the same as a monolingual claiming their ability of another language.
Say, I can now read Spanish but it does not mean I am able to use the language in my daily exchanges. Therefore, I don't count myself as a trilingual. A trilingual is my Chinese/Indian friends who can switch from all three languages they have (English, Mandarin/Tamil and Malay) and form a sentence using words from those languages.
So to be classed as bilingual or more, in my personal opinion, you need to be able to understand the languages to a certain extent where you use both languages without hesitation.In short, even your thoughts are formed around these languages subconsciously and that's the definition of being able to speak more than a language to me.