Now we are prepared to say the phrase that concerns us most - "fluent Hebrew!"

So, how do we say "fluent"? We use the word שׁוֹטֵף in this sense, and you are prepared already to use the feminine version of it - עִבְרִית שׁוֹטֶפֶת.
Now you can say:אֲנִי מַבְטִיחַ לְדַבֵּר עִבְרִית שׁוֹטֶפֶת כְּבָר בְּשָׁנָה הַבָּאָה! :)
("I promise to speak fluent Hebrew next year!")
There is more to be said about the word שׁוֹטֵף. Actually, it means "running" about liquids, like in "running water!" Or "washing" and "rinsing" - anything that has to do with cleaning with running water.

Examples:שָׁטַפְתָּ אֶת הַפֵּרוֹת?
תִּשְׁטֹף אֶת הַיָּדַיִם, בְּבַקָּשָׁה!

*An interesting expression with this word and a virtual plague for freelancers is שׁוֹטֵף פְּלוּס שִׁשִּׁים - the practice to pay 60 (or 30) days after the the end of the month in which the work was performed, as many big companies do. I think there is no special English equivalent... just "the payment is due in 60 days" or something.