I've been doing personal research in Second Language Acquisition by reading a book on the subject (Understanding Second Language Acquisition -- by Lourdes Ortega) and I've become convinced that the L1 has a huge effect on the way an individual thinks and communicates.
However, as a very young child I first spoke Russian at a low level, and then spoke Hebrew from the age of about 5 until 10, where I soon after lost Hebrew and English became my native language.
I now speak English at a native level with no apparent accent and am maintaining an intermediate level of Russian and am re-learning my Hebrew from ground up.
Two questions arise in my mind:
Is it possible that my thinking in general and communication in English is suffering because my L1 is still Hebrew, yet I lack the vocabulary to communicate?
Has my L1 become English at an age as late as 10-11?
Now a question that can potentially be answered:
If I were to re-learn Hebrew, how would I be able to determine whether my L1 is indeed English or in fact Hebrew, or perhaps even a mix of the two (three if you include Russian)? Is there some sort of analysis I could perform on myself?