What does this mean!!!!?

Hey everyone, just have a quick question that I may know the answer(s) to. But i'll ask anyway.
Today I was out in some pretty tiny waves with my 6'8 Fish and could catch the waves, but when I'd stand up, I would lose the wave.
I could easily stay prone and take the wave for most of its length.
I think it' means a few things-
-I would need a bigger board for these size waves
-The waves just aren't strong enough
-My body weight and board combination are too much for the power of the waves.
Thoughts?
Today I was out in some pretty tiny waves with my 6'8 Fish and could catch the waves, but when I'd stand up, I would lose the wave.
I could easily stay prone and take the wave for most of its length.
I think it' means a few things-
-I would need a bigger board for these size waves
-The waves just aren't strong enough
-My body weight and board combination are too much for the power of the waves.
Thoughts?