I studied English for six years all together in junior high school and high school, but I don't really remember speaking English at all.
Even though I learned English for three years in junior high school and another three years in high school, I can't recall speaking much English during our classes.
ーI studied English for six years all together in junior high school and high school, but I don't really remember speaking English at all.
「中高と全部合わせて６年間英語を勉強したけど、英語を話したことを全然覚えていない」
to study English for six years で「６年間英語を勉強する」
all together で「全部合わせて・まとめて」
junior high school で「中学校」
high school で「高校」
at all は否定文で使うと「少しも…でない」
ーEven though I learned English for three years in junior high school and another three years in high school, I can't recall speaking much English during our classes.
「中学で3年、高校でもう3年、英語を学んだけど、授業中に英語を話したことを思い出せない」
recall で「思い出す」
during our classes で「授業中に」
ご参考まで！
I studied English for six years in junior high and high school, but I don't remember ever speaking it.
そのような状況を説明する場合、「I studied English for six years in junior high and high school, but I don't remember ever speaking it.」という表現が適切です。
これは、「中高合わせて６年間英語を学んだけれど、実際に話した記憶がない。」という意味になります。
カナダ 
アメリカ合衆国 
