I always admire my parents, because they raise and care for me/they raise and take care of me
and then they always love me.
When i was a child I had thought /thought that their love for me was their duty for me when i was childhood.
at that time i was stupid. and then now i am also still stupid
Because I don't give them much more love than they gave it to me /i don't love them more than they love me
i always regret that
so I want to show them my heart /how i feel and to say that I love you them
maybe i can't tell my parents because i am shy and stupid.

It's not too late to show them how much you love them :)