我不是很理解你的意思 怎么说？

I don't/didn't quite get you.
I don't/didn't quite follow you.
I don't/didn't catch you.

I don't understand what you meant.
I'm not following you.

我不是很理解你的意思
I don't quite follow you.
or
I don't understand what you mean.

I don't understand your meaning very much.

I didn't follow you
I didn't get you

I don't understand what you mean very much.

I don‘t understand your meaning ！