I speak Indonesian and Javanese as my native language, "forced to learn" Japanese, English, Malay, and a bit of Chinese here in Japan.
Contrary to common opinion, I regret that I learn and speak a lot of languages because I don't feel adequate enough in any of them, even my native language. Being able to use a lot of language really broaden your view, but at the same time, you will incline to develop multiple personalities/conscious in your effort to speak like the native. I find it difficult to express myself in a "constant" way regardless languages, hence the feeling of inadequate.
I was raised in Galician but taught to read and write in Castillian (Spanish), and grew up in an environment where almost all media, signs, labelling, ..., were in Castillian. Programming related learning and work has taken most of my studying since my teen years, and I did that exclusively in English. Because of this, I estimate English is already the language in which I've done most of my reading and a fair share of my writing.
I can relate to what you say, because for quite a time when trying to express myself formally I used to end up resorting to a lot of transliterated Castillian constructs and phraseology. Other times, ideas would come in English and I'd try and find a Galician equivalent. I only got past that after a conscious decision to immerse myself in Galician and Portuguese literature. Sometimes I still feel like learning my native language as a second language.
And I'd be at a loss if I had to talk about programming related concepts in anything but English. I'd have to reinvent the vocabulary as I go. My own scribbled notes for personal use are written in a patois that is mostly Galician generously sprinkled with English.
I run into quite a few people that were raised either first half in japanese and second half in english, or vice versa, and many of them seem to have this difficulty, not being quite up to the highest level of fluency in any language. They can get by perfectly well in both, but neither language is perfect.
